FCP psi

It can be noted from the two examples, if the choke line friction loss pressure is used for the kill calculations, the ICP and FCP will over pressure the well by 450 psi at start-up, and 513 psi at FCP. This extra pressure could cause formation damage. It is also unnecessary to hold this extra CLFL pressure in the well, as, in using the riser SCR pressure for our calculations, we can then back off the value of CLFL from the well by auto-choke manipulation (casing gauge) during the start-up...

Tool Joint Consideration

The buoyed weight of the drill pipe may not be great enough to overcome the upward force exerted by the annular pressure, as the larger diameter tool joint enters the annular preventer. This can be determined by attempting to lower the tool joint through the annular preventer after the closing pressure has been regulated. The annular pressure is low enough to allow the pipe body to strip through the annular preventer, but will not allow the pipe to move as the tool joint goes through the...

Shut In Procedure While Out Of The Hole

Note that monitoring equipment should always be in use when the hole is open. (2) OPEN choke line valve. (failsafe or HCR valve) (4) CLOSE choke. If not a positive shut off, then close a downstream valve to record pressure. (5) Alert supervisor. Read and record casing pressure and times. Check pit and trip volumes for pit gain. The operators representative shall decide what steps to make from this point. The main options available are (b) Bull heading down the kill line.

Surface Subsea Bops While Wireline Logging

Direct the wireline loggers to cease operations and close the well on the upper annular. Open kill line valves and begin to record shut in pressure and pit gain. Pass word to the OIL COMPANY REPRESENTATIVE and SENIOR DRILLING CONTRACTOR REPRESENTATIVE of the well condition. NOTE If at all possible the wireline should be pulled or stripped out of the hole. If the line needs to be cut and dropped, a surface hydraulic cable cutter should be used. The shear rams should be considered as a last...

Failing To Fill The Hole Properly

This is one of the common causes of kicks. If the fluid level in the hole falls, than a reduction of bottom hole pressure must occur since the length of the fluid column has shortened. As drill pipe and collars are pulled out of the hole, a volume of mud equal to the volume of steel which has been removed, must be added to the hole to keep it full. If this is not done the length of the mud column is reduced, thereby lowering the bottom hole pressure. Once this pressure drops below formation...

Contents

1.2 SOFT SHUT-IN PROCEDURE WHILE DRILLING - FIXED RIG 3 1.3 SOFT SHUT-IN PROCEDURE WHILE TRIPPING - FIXED RIG 3 1.4 HARD SHUT-IN PROCEDURE WHILE DRILLING - FIXED 1.5 DIVERTER PROCEDURE WHILE DRILLING - FIXED RIG 4 1.6 HARD SHUT-IN PROCEDURE - FLOATING RIG 7 1.7 SOFT SHUT-IN PROCEDURE WHILE DRILLING - FLOATING VESSEL 7 1.8 SOFT SHUT-IN PROCEDURE WHILE TRIPPING - FLOATING VESSEL 8 1.9 SHUT-IN PROCEDURE WHILE OUT OF THE HOLE 8 1.10 DIVERTER PROCEDURE WHILE DRILLING 9 1.11 SURFACE & SUBSEA BOPS...

Maximum Allowable Annular Surface Pressure

MAASP PFB - Head of Mud to Shoe (psi) MAASP Gfb Gmud x Shoe Depth (True vertical) (Psi) MAASP (Max Equiv.Mud wt Current Mud wt) x Shoe Depth x 0.052 (psi) (True vertical) rilling S Well Services Training Kill Mud Weight _ Original Mud Weight + SIDPP (ppg) (ppg) Depth, (True Vertical 0.052 (ppg) Depth (True Vertical)x 0.052 ICP Slow Circulating Rate Pressure + SIDPP (psi) FCP m , . Kill Mud WT

One Stage Kill

The well is closed in as quickly as possible to keep kick size to a minimum. If at all possible, pipe is to be run back to bottom, by stripping in, before starting the kill. Appropriate procedures for this are discussed under 'Stripping'. While stripping in, variations in bottom hole pressure due to gas migration may be dealt with using the Volumetric method discussed in Section 'Kill Methods'. DO NOT RUN BACK IN WITH THE WELL OPEN. If the well is underbalanced, a further influx will occur and...

Two or Multi Stage Kill

Bottomed Gas Well

If return to bottom is not practicable, the well must be brought back to balance to allow staging back to bottom and a final kill. The diagram Figure 4 illustrates a situation with a well closed in, bit off bottom. Note that the shut in drillpipe and shut in casing pressure are reading the same. If all of the influx is below the bit, this is likely to be so. The effect of a slug of heavy mud in the drillpipe, for tripping, would be to lower the drillpipe figure somewhat (perhaps 30 or 40 psi)....

Pressure Changes At The Choke When Gas Reaches The Choke Line

If gas is being circulated out of the well through a long choke line, a sharp reduction in annulus pressure occurs when the gas reaches and fills the choke line. As the mud in the choke line is rapidly replaced by the gas, the choke size must be quickly reduced in order to maintain sufficient bottom hole pressure on the formation and avoid taking a secondary kick. As the gas is circulated out from the choke line, the mud replacing it will cause a sharp increase in hydrostatic pressure and...

During Tripping

The indication of the presence of a kick is If this indication is not noticed at an early stage, it should become progressively more obvious. In the extreme case the hole would eventually stay full, or flow, while pulling out. This may sound ridiculous, but it has occurred. b) HOLE KEEPS FLOWING BETWEEN STANDS, WHILE RUNNING IN. The presence of some or all of these indications require that a flow check be carried out to determine whether or not a kick is in progress. This procedure is described...

Indications Of Approaching Balancerising Formation Pressure

Some of the following indications are signs that abnormal formation pressures are being encountered and the formation pressure will eventually balance or exceed the bottom hole pressure exerted by the mud column. Others are simply signs that formation and bottom hole pressures are approaching balance. These are sometimes referred to as secondary indications of a kick. These indications can be summarised as Torque and Drag, Fill on Connections Each is discussed now in more detail 1.4.1 Drilling...

LogRN logWD

Where R Rate of penetration, ft hr The hydraulics and formation drillability were not included in the equation for normalised drilling rate, since their effects were considered negligible within certain limits. The authors provided correlation's of field measured pressure data and 'd' exponent calculations. They showed that formation pressure could be estimated by first plotting 'd' values in shale versus depth, on semilog paper, and determining a normal trend line of decreasing values with...

Well Control Gas Cutting

The appearance of gas cut mud at the surface usually causes an over-reaction of increasing mud density. Where little or no pit level gain has been recorded, this reaction is probably incorrect. The reduction of bottom hole pressure owing to gas cutting has been shown previously. However due to the compressibility of gas, a fifty percent gas cut of mud at the surface changes the bottom hole pressure at 20,000 feet by only 100 psi. Gas cutting must not be ignored, but regarded as a secondary...

Soft Shutin Procedure While Drilling Floating Vessel

(1) When a possible indication is observed, stop rotary and pick up string to the predetermined height required for spacing out. (2) STOP pumps. Check for flow. If positive. (3) OPEN failsafe valve on BOP stack (valve on the choke line). (5) CLOSE choke. If this choke is not a positive shut-off type, it is necessary to close a valve (ideally just downstream of the choke) in order to read well pressures. (6) Alert supervisors. Check pit gain. Read and record pressures and times. If pipe is to be...

Soft Shutin Procedure While Drilling Fixed

(1) When a possible indication is observed, stop rotary, pick-up off bottom until spaced out. (2) STOP pumps. Check for Flow. If positive, then (3) OPEN choke line valve at the BOP stack (often called HCR valve or 'F' type valves.) (5) CLOSE choke. If this choke is NOT a positive shut off type, it is necessary to close a valve (ideally just downstream of the choke) in order to read well pressures. (6) Alert supervisors. Read and record pressures and times. Check pit volume gain. (7) If...

Annular Preventer Only

When the annular pressure is 1000 psi or less, stripping with the annular preventer is preferred over the combination preventer. This is because it is faster, easier for the rig crews to learn and is a relatively simple operation to control. Certain considerations have to be made concerning the accumulator bank, before stripping with any preventer combination. These considerations are a) The accumulator bank should be fully charged and isolated from the closing pumps. This provides a power...

Abnormal Formation Pressures

Abnormal pressures and their causes are discussed in the 'Pressures' section. Generally, if a permeable zone containing fluids pressured above the normal gradient for the area is to be penetrated, then appropriate mud weights must be run. Where possible, prediction of likely abnormal pressures should be carried out, both during well planning and during drilling. A number of trends will signal changes in formation pressure. Sometimes low permeability formations known to be abnormally pressured,...

Pump Pressure Decrease Pump Stroke Increase

Invading formation fluid generally reduces the total head of fluid in the annulus. The head of mud in the drillpipe is unaffected, so that there is a tendency for fluid to 'U-tube'. This means that the pump does not have to provide so much energy and this may be seen as a pump pressure reduction. Depending on the rig installation, a small increase in pump rate may also be noted. The effect is small, and may not be noticeable. The same effects are seen if a washout occurs, so it is necessary to...

Regulators

Each subsea control pod contains two regulators one to regulate pressure for the manifold and one to regulate the pressure for operating the annular preventers. Some control systems incorporate a third regulator so that the operating pressure of each annular preventer can be individually manipulated. Typical regulators are 1 V2 hydraulically operated, stainless steel, regulating and reducing valves. As shown in Figure 61 the output line of each regulator is tapped and the pressure routed back...

If possible a small accumulator should be installed in the annular preventer closing line to dampen

13 Start running pipe while bleeding mud from the casing using the hand adjustable choke. Run the pipe slowly and evenly to avoid pressure surges. Measure the amount of mud bled off through the choke and the mud that leaks by the annular BOP to ensure that the total volume equals the volume of pipe run. Example 1 Stripping 4 W OD 16.6 lbs ft, H-90 Drill Pipe From Table 1, Total Displacement of Drill Pipe The total mud bled off and the leakage from the annular BOP should be 1.899 bbls. for each...

Gas

The volume occupied by a quantity of gas is related to both pressure and temperature. The property means that during the circulation of a gas kick, the volume of the gas must be allowed to expand in order to drop the pressure as it comes to the surface. Considerable changes in casing pressure are seen, along with variation in pit levels. For this reason, gas kicks are the hardest to deal with, and the majority of kicks discussed in well control literature are gas kicks. A...

Torque and Drag Fill On Connections

Increases in torque and drag often occur when drilling underbalance through some shale intervals. As the result of this fluid in the shale expands, causing cracking, spalling and sloughing of the shales into the wellbore. This condition can cause a buildup of cuttings in the annulus, excessive fill on connections and trips, a buildup in torque and drag and eventually stuck pipe. Increases in torque and drag can be a good indicator of abnormal pressure, especially if used with other indicators.

RIGTRAllM

Controlled Well

Figure 7 Floating Rig, Determining Choke Line Friction Losses Alternative Way Figure 7 Floating Rig, Determining Choke Line Friction Losses Alternative Way Choke Line friction losses are not significant at slow pump rates in shallow water depths. In deep water they can be significant, and must be compensated for. With significant choke line friction losses, the important phase of the kill operation will be at start of the kill operation, when the pump is being brought up to the required kill...

Surcharging of Shallow Formations

Poor Boy Degasser Pressure Gauges

This may be a natural effect, as often occurs in fault zones, or an artificial one. In the case of a naturally occurring fault, the zone of broken rock, or 'breccia', at the fault itself may allow fluid seepage over part of its extent. This can result in shallow formations becoming 'charged up' with formation fluid at pressures much greater than normal for their depth. This is shown in Figure 7. In some old established oilfields a similar effect has occurred when 'downhole communication' or a...

Volume Pumped bbl

Figure 10 shows a typical graph for a leak-off test carried out in this way. Here mud has been pumped slowly in quarter-barrel amounts. After each quarter barrel, the pump is shut down and pressure allowed to stabilise for 30 seconds or so. This value is noted on the graph and pumping continued. Some companies graph both pumping and static pressures. The two lines should run approximately parallel until breakdown occurs, at which point they diverge. The leak-off pressure, PLO, determined by...

Floating Vessel

Drilling Operations Procedures

It should be noted that the shut-in procedure on a floating vessel differs from that of a fixed rig. a The floating rig tends to move. b The BOP stack is remotely located - usually on the sea floor. c The string can be hung off during a kill, with a tool joint lowered onto closed pipe rams, and string weight hung on these rams. d A space distance, to prevent a tool joint being opposite the BOP rams must be calculated and available immediately to the driller. Where necessary allowance for tidal...

Salt Beds

Salts do not, have the same structural properties as rocks. Salt is plastic. It deforms and flows by re-crystallisation. Its properties of pressure transmission are more like fluids than solids. Salt has very little rock frame structure and depending on the actual composition type of salt and amount of water of crystallisation and temperature, massive salt could have pressure approaching 1 psi ft. These salts can be drilled with lighter mud weights because, although it behaves as a fluid, salt...

Soft Shut In Procedure While Tripping Floating Vessel

1 When a possible sign is observed, set top tool joint in the slips. 2 Install a full opening, fully opened safety valve in the drill pipe. CLOSE the valve once installed. 3 Remove slips and pick pipe up to predetermined height for space out and check for flow and check trip volumes. 4 OPEN choke line valve at BOP stack failsafe valve . 6 CLOSE choke. If this is not a positive shut off type, it is necessary to close valve just downstream of the choke in order to read well pressures. 8 Stab...

Mud FillUp Line with Stroke Counter

In this procedure, the hole is 'topped up' at regular intervals using a fill-up line, and the required mud volume is then noted. Typically this will be done after every five stands of drill pipe, and after every stand of drill collars. This may be stretched, depending on circumstances, to one fill-up every ten stands of drill pipe or two stands of drill collars. The mud volume added may be calculated either by noting the number of pump strokes required from a pump of known displacement, or by...

Square inches

Hydrostatic Pressure

Hence a one foot high column of 1 ppg fluid would exert 0.052 psi on its base. This is the same as saying the PRESSURE GRADIENT of the fluid is 0.052 psi ft Alternatively, it can be written as follows ppg -r 19.23 psi ft On Pressure Control Worksheets this 19.23 was sometimes rounded up to 20, for ease of working in pre-calculator days. Figure 1 - Hydrostatic Pressure Vertical Height Vessel Shape Figure 1 - Hydrostatic Pressure Vertical Height Vessel Shape

Casing Selection

The size, weight and grade of casing required for any well will be defined by the maximum loads to which the casing may be exposed. Casing size is dictated by well depth and the type of completion required. The weight and grade of the casing can then be determined, taking appropriate safety factors into consideration. This is to ensure that casing strength is sufficient to ensure proper well control. The three primary load to be considered are collapse pressure, burst pressure and tension. The...

Splitting Packing Units

Packing Unit Hydril

Packing unit replacement is also possible with pipe in the hole. After removing the worn packing unit, cut the new packing unit as shown. The cut should be made with a sharp knife, as this will not affect the efficiency of the packing unit. Spring segment apart with a pry bar for easier cutting. Spring the packing unit open sufficiently to pass around pipe, drop unit into position in BOP body, and replace head. Figure 29 - Proper Method for Cutting Through Packing Unit with a Sharp Knife Figure...

Flowline Temperature

The temperature gradient in the transition between normal and abnormal pressure zones often increases to about twice the rate of the normal temperature gradient. Increases of the mud temperature at the surface can also indicate the top of an overpressured section. Consideration must be given to circulation times, trip times, connection times, stabilised temperature after tripping, temperature of mud at suction pit, and other factors such as water depth. An increase in flowline temperature when...

Factors Influencing Maximum Casing Pressure

The maximum casing pressure resulting from circulating out a kick while maintaining constant BHP is influenced by the following factors c Difference between mud and formation pore pressure gradients Original Mud Weight versus Kill Mud Weight d Density and type of kick. Gas kicks are worse e Annular volume capacity. Pressures increase as annular capacity decreases because the gas bubble is 'longer' g The type of kick killing method used e.g. the Wait and Weight Method causes the lowest casing...

Continuous Circulating Trip Tank

Trip Tank Drilling

The trip tank, as shown in Figure 1 can be set to continuous gravity feed, or it can use pump feeding. The advantage of this system is that the hole remains full at all times, and the volumes used can be continuously and accurately maintained. The main drawback to this system is that the trip tank does not contain enough mud to permit a full trip without refilling. The drill crew should develop a routine of checking the trip tank level frequently and therefore be aware when refilling is...

NOTE In the example well show assume that loss of circulation cannot occur

Trip Tank Fill Welbore

Figure 2 shows drill pipe run into a 10,000 ft hole filled with 10 ppg mud and then closed in with the BOPs. The drill pipe is fitted with a back pressure valve and the weight of the drill pipe is sufficient to overcome the tendencies of the well bore pressures to push the drill string out of the hole. A valve and a check valve are installed between the well bore and the gas sand, to simulate flow from formation. 5200 psi due to mud hydrostatic pressure 0 psi Figure 3 shows that the adjustable...

Soluble Gas Kicks

A gas kick where some or all of the gas goes into solution in the drilling fluid can be very dangerous and difficult to handle. If the gas is in solution, it does not normally expand until it comes out of solution. As the fluid nears the surface, the drop in pressure and temperature may allow gas to break out from the fluid. The normal near-surface rapid expansion then occurs when not expected, in what otherwise appeared as an easily managed liquid kick. This effect is very likely to occur in...

AAnnular to Ram Stripping

When stripping with ram preventers, the same principle applies to packing element wear as the annular preventers. The lower the closing pressure while stripping, the longer the life of the sealing element. Initially CLOSE the ram preventers, using 1500 psi pressure, and then adjust the regulator to reduce the pressure, depending on the pressure of the well. The annular preventer should also be closed with 1500 psi and the regulator adjusted to sealing pressure with a minimum of 600 psi.

List Of Abbreviations

Hmud Head of Mud or Hydrostatic Pressure of Mud usually psi . Gmud Pressure gradient of mud usually psi foot . PF Formation Fluid Pressure usually psi . PFB Formation Breakdown Pressure or Formation Fracture Pressure or Formation Breakdown Pressure Gradient usually psi foot . Maximum Equivalent Mud Weight, to produce Formation Breakdown Pressure at Shoe. Maximum Allowable Annular Surface Pressure usually psi . Surface Pressure, which if exceeded may cause leakage of whole mud into formation of...

Storm Valve

Regan Fast Shut Off Coupling

In the event that the string has to be hung-off whilst waiting on weather or pulling the BOP stack for repair, the well can be secured by using a storm valve See Figure 70. This valve is run above a retrievable packer and serves both as a means of sealing off the drillpipe and as a means of releasing the running string. It is a sleeve type valve operated by left hand rotation. As the upper mandrel is backed out of the upper body, it pulls up and closes the valve sleeve. Continued rotation then...

Balance Of Pressures

Kill Mud Weight

Once the well is shut-in, providing nothing has broken down, the pressures in the well will be in balance. What is lacking in hydrostatic head of fluid in the well is now being made up by surface applied pressure on the annulus and on the drillpipe. This allows us to determine what the formation pressure is and hence what kill mud weight is required to achieve balance. On the drillpipe side of the U-tube See Figure 1. Formation Hydrostatic Pressure Shut In Drill Pipe Pressure of Mud in...

Gas Expansion

Gas Well Annular

During a kill the gas is not allowed to expand freely, since this would result in the well 'unloading'. Therefore a CONSTANT BOTTOM HOLE PRESSURE slightly above FORMATION PRESSURE is maintained throughout the kill. The diagrams Figure 2 and Figure 3 show theoretically how casing pressure and pit volume vary during the circulating out of a gas kick, using the Wait and Weight method, while holding BHP constant. Figure 2 assumes a single bubble has entered the well. As previously mentioned the...

Severe or Total Losses

Where losses are too severe to maintain or are total, several options remain a Pump lost circulation material down the annulus. In most instances, losses occur at the casing shoe, in which case Lost Circulation Material LCM pumped down the annulus will often reach the shoe more rapidly. Pumping down the annulus further helps to reduce influx and to avoid bit plugging, since the total fluid head is greater. b Placing a heavy slug of mud on bottom. A heavy slug of mud can be spotted to fill the...

General

Lost circulation may occur as partial or total loss of returns. In the relatively soft shales of the marine basins, partial losses are relatively common during well kills. In this case, the well is killed using the standard method. With total losses, as may occur in older hard rock country, well control is much more difficult. There are a number of signs which, taken together, indicate that losses are occurring. The most reliable of these is the pit level, which may either drop or, more...

Gas Migration

If a gas kick enters a well, the pressure of gas at that point is formation pressure PF , ignoring any skin damage effects . Gases are compressible and thus store energy for later release. Considerable energy can be stored in this way. Liquids, in contrast, are virtually incompressible, and because little or no change in volume occurs little energy can be stored. This characteristic of gas means that when a well is shut in with a gas kick, the gas in the well retains the prevailing pressure at...

Well Control From A Floating

Well Control

Well Control on a floating rig can present special problems that are not encountered on land or fixed bottom rigs. These problems can be summarised as follows. Kick Detection can be more difficult due to the motion of the vessel. Mud surges in a flow line or fluid movement in mud pits can make the detection of small inflows into the well very difficult to detect. Fracture Gradients. Fracture gradients are a function of overburden and formation fluid pressures. As water depth increases the...

Diverter Procedure While Drilling

1 When a possible indication is observed, STOP the rotary, pick up until spaced out. 2 Shut down pumps and check for flow. If positive 3 OPEN diverter line valves- check that flow will be diverted to downwind side of rig. 5 CLOSE diverter annular BOP. 6 Start pumps ideally to pump water at maximum possible rate, for lubrication. NOTE On many rigs, there is a mechanical interconnection to prevent the diverter annular closing, until the diverter line valves are opened. This is to prevent an...

Constant Bhp Kill Methods

Methods Well Kill

There are three 'constant bottom-hole pressure' kill methods in common use today which are Wait amp Weight Method also known as the 'Engineer's Method' These three techniques are very similar in principle, and differ only in respect of when kill mud is pumped down. In the Driller's method, the kill is split into two circulations. During the first, the kick fluid is circulated without changing the mud weight once the kick is out, the mud is weighted up and pumped around the well on the second...

Redundancy

Problem Shaffer Spm

The two subsea control pods are functionally identical. When a pilot control valve rams close for example is operated on the hydraulic control manifold a pilot signal is sent down both umbilicals so that the associated SPM valve in each pod 'fires'. If the pod selector valve is set on yellow then power fluid is sent only to this pod and it is only through the SPM valve in this pod that the fluid will reach the ram operating piston. The pod selection has no effect on the pilot system. Once the...

Soft Shutin Procedure While Tripping Fixed

1 When a possible sign is observed, set top tool joint in the slips. 2 Install a full opening Safety valve on the drill pipe. Close the valve once it is installed. 3 Pick pipe up, check for flow. Check trip volumes. 4 OPEN choke line valve at Bop stack. HCR valve . 6 CLOSE choke. If this is not a positive shut-off type, it is necessary to close a valve just downstream of the choke in order to read well pressures. 8 Stab IBOP Grey Valve and open full opening safety valve. 9 Read and record...

Umbilical Hose

Umbilical Hose Bundles And Reels

The umbilical transmits all power fluid and all pilot signals from the surface to the subsea control pods. Hydraulic pressure from the regulated side of the subsea regulators is also transmitted through the umbilical to pressure readback gauges at surface. The power fluid is supplied only to the umbilical of the selected active pod, whereas pilot pressure is normally supplied to both the active and inactive pods. Figure 63 Hose Reel Control Manifold Figure 63 Hose Reel Control Manifold rilling...

Drill Pipe

Gas Well Drill Pipe

Figure 5 shows that the adjustable choke has been OPENED and exactly one barrel of mud, including leakage past the BOP, has been bled. a Pressure in the gas sand 5400 psi b Bottomhole pressure 5400 psi c Surface pressure 450 psi Note that the wellbore pressure has returned to the original value Figure 3 . By bleeding one barrel of mud, the gas bubble expanded back to its original volume and the wellbore pressure dropped 50 psi. From this, the following conclusions can be made 1 If mud is bled...

Low Choke Method

After observing the maximum allowable surface pressure, choke adjustment may be made to hold the casing pressure constant. This will steadily reduce BHP. This procedure is to be limited at most to a 150 psi drop in BHP. The effect of annular friction loss acts as a small safety margin before influx occurs. In many cases this procedure allows time for the influx to be circulated past the casing shoe before a further significant influx occurs. This depends, amongst other things, on formation...

Rams Subsea

Besides sealing off the annulus, the pipe rams are able to support the weight of the drill string up to some 600,000 lbs if it needs to be hung off on them killing operations or during periods of bad weather. To do this safely, the rams must be able to be locked in the closed position. Cameron U-type preventers use a wedge lock device. This is a tapered wedge, hydraulically operated, which moves behind the tail rod of the ram operating piston thus holding the ram firmly closed. The wedge can...

Mud Salinity

Specific mud characteristics measured in the suction pit are compared with measurements after circulation. Mud resistivity, chloride ion content, pH variations, and other specific ions are closely monitored. Gains or losses of specific ions are correlated to down-hole pressure differentials by proprietary logging methods Delta Chloride Log and used in predicting mud weight requirements. Invasion of the drilling mud by formation water can sometimes be detected by changes in the average density...

Well Data

Gradient Breakdown pressure at shoe DC OH Capacity DP OH Capacity MAASP Assume SIDPP Influx gas Formation pressure 0.0291 bbls ft 800 ft Collars 0.0459 bbls ft 0.72 - 0.52 x 5000 ft 1000 psi 500 psi 0.12 psi ft 500 10000 ft x 10 x 0.052 5700 psi 1250 ft This will cover the collars and 450 ft of pipe. Collars 23.28 bbls Around the pipe 450 ft x 0.0459 20.655 bbls Total length 1250 ft Total volume 43.935 bbls Step B 1250 ft converted to a volume below the shoe. 1250 x 0.0459 57.375 bbls...

Annular Diverter

Sub Sea Annulars

1.1 AUXILIARY WELL CONTROL EQUIPMENT 3 1.4 STRIPPING OPERATIONS 39 1.5 ANNULARS CAMERON 'DL' 40 1.6 ANNULARS - HYDRIL 'GK' 43 1.7 PACKING UNIT REPLACEMENT - SCREWED HEAD 45 1.8 SPLITTING PACKING UNITS 46 1.9 ANNULARS - HYDRIL 'GL' PREVENTER 47 1.10 HYDRIL PACKING UNITS SELECTION 50 1.12 MUD GAS SEPARATOR POOR BOY DEGASSER 57 1.13 FLANGED AND RING GASKETS 60 1.14 HYDRAULIC BOP CLOSING UNIT 67 1.16 SUBSEA BOP CONTROL SYSTEMS 72 1.18 FAIL SAFE VALVES SUBSEA 106 1.19 SUBSEA ANNULAR HOOK-UPS 108...

Secondary Well Control Hmud Pf

If for any reason the effective head in the wellbore should fall below formation pressure, an influx of formation fluid kick into the wellbore would occur. If this situation occurs the Blowout Preventers BOPs must be closed as quickly as possible to prevent or reduce the loss of mud from the well. The purpose of Secondary Well Control is to rectify the situation by either a allowing the invading fluid to vent harmlessly at the surface, or b closing the well in. i.e. providing a surface pressure...

Sediment Compression See Figure

In areas where rapid deposition has given rise to shale bodies, sur-pressures develop as a result of compression. This is particularly prevalent in the basins where much of the offshore drilling is taking place. However, evidence of compression may be found in almost any area. When shale bodies are deposited, porosity of the clay shale is more than 50 . As deposition continues, clays compact under the weight of material above. As porosity decreases, the expelled waters find their way out...

Regan Fast Shut Off Couplings

If a kick is taken whilst the Kelly is removed from the drill string, flow up the pipe might be so strong that it is impossible to stab a safety valve. In this case, a fast shut-off coupling See Figure 69 which is designed to be dropped over the drill pipe and automatically latch under the tool joint can be used. The coupling is very heavy to assist in stabbing and has a Kelly cock either integral with it or screwed on top of it. It should be ensured that any drill pipe that might be used has...

Drill Rig Kill Line

Kill Line And Drill Pipe

If this start up procedure is used on a floating rig with significant choke line friction losses, bottom hole pressure would increase by a pressure equal to the friction losses. This overpressure could cause damage to the formation. There are two methods that can be implemented to compensate for this over pressure choke line friction losses . As the pump is being brought up to kill speed, the casing pressure is being reduced by an amount equal to the choke line friction losses. With the pump at...

Hangoff Procedures During Bad Weather

Whilst 'Waiting on Weather' it might be necessary to hang the drill string off from the wellhead or BOPs. In severe cases, it might also be necessary to disconnect the riser from the BOP stack. The decision to 'hang-off should be taken to allow sufficient time for the bit to be pulled safely into the casing shoe. A natural tendency for the driller to pull up too quickly could perhaps induce swabbing and a possible kick situation later. The preferred method to hang-off the string is to use a...

Hard Shutin Procedure While Drilling Fixed

1 When any indication is observed while drilling that the well maybe flowing, stop rotating the drill string, raise the drill with pumps on until spaced out. 2 Stop pumping and check for flow, if positive 3 Close annular or pipe rams. 5 Call supervisor and commence plotting a graph of shut in drill pipe pressure. Check pit volume again. 6 Refer to API RP 53 for advantages and disadvantages of the hard shut-in. NOTE Choke in closed position while drilling. In any shut-in procedure it is prudent...

Heaving Shales

Excessive volumes of shale cuttings on the shaker may be an indication of an underbalanced condition. Shale is usually very porous, but has little or no permeability. Fluids in the pores are subjected to formation pressure, but are not able to flow. However, if a differential pressure exists from the formation to the well bore, such as in the case of abnormal pressure, the fluid pressure causes weakening of the walls of the hole and spalling or heaving of shale into the hole. At the surface an...

BRam to Ram Stripping

The following general guidelines apply to all pipe ram preventer to pipe ram preventer stripping. i The same general techniques are applied in ram to ram stripping as outlined in annular to ram stripping. ii When stripping with ram preventers, the lower the closing pressure, the longer the life of the sealing element. iii The pipe ram above the drilling spool should be used as the primary stripping preventer. iv The pipe ram immediately below the drilling spool should only be used to strip...

Hose Reels

The hose bundles are mounted on heavy duty reels for storage and handling and are connected to the hydraulic control manifold by jumper hoses. The reels are driven by reversible air motors and include a disc brake system to stop the reel in forward or reverse rotation. When the subsea control pod is run or retrieved, the junction box for the jumper hose is disconnected from the hose reel. However in order to keep selected functions 'live' during running or retrieval operations, five or six...

Formation Fracture Pressure

Formation fracture pressure, or formation breakdown pressure is the pressure required to rupture a formation, so that whole mud can flow into it. The symbol PFB is usually used to denote this pressure See Figure 10. Commonly this is expressed as a pressure gradient, GFB, with the units of psi foot. The formation breakdown pressure is usually determined for formations just below a casing shoe by means of a leak-off test. This test of the formation strength, also known as a formation integrity...

Differential Fluid Pressure

Reservoir Fluid Pressure

The classic example of a differential fluid column is the Artesian Well. Here an aquifer, or water bearing permeable layer outcrops in the hills. The drive pressure from such a reservoir equals the fluid head at any point See Figure 5. Drilling into the aquifer out on the plains, as shown in the diagram, only a relatively short column of well fluid is available to balance a big column of formation water. Hence an abnormally high pressure gradient has to be held if the well is not to blow out....

Pre Spud Pressure Estimation

Determination of pore pressure formation fluid pressure is estimated by a number of methods. These methods rely on establishing the 'Normal Trend' of measured shale properties with depth and subsequently identifying any departures from the normal trend which could indicate 'Overpressure Zones'. Each method used is based on shale compaction which is, briefly, described as follows In a sedimentary basin the continuous deposit of muds and silts causes a build up of material which squeezes or...

Riser Collapse

Calculate Api Collapse

In water depths over 1500 ft riser collapses can be a potential problem when a shallow gas kick is being diverted and all fluid is evacuated from the riser. The collapse resistance of the riser may be reduced by the considerable bending loads applied to the riser due to tension, weight and current forces. If this problem is considered a possibility, then a riser joint fitted with a special differential fill-up valve can be used. This valve automatically senses the loss of hydrostatic pressure...

Insufficient Mud Weight

The hydrostatic pressure exerted by the column of mud in the hole is the primary means of preventing kicks. Insufficient mud weight can result from penetration of an unexpected, abnormally high-pressure zone, or be due to deliberate underbalance drilling methods in field development wells. Accidental dilution of the mud with make-up water, in the surface tanks, is a relatively common occurrence, and must be guarded against. With water base muds and fast drilling, it is common to add...

Diverter Procedure While Drilling Fixed

Annular Bop Diverter

1 Where shallow casing strings or conductor pipe are set, fracture gradients will be low. It may be impossible to close the BOP on a shallow gas kick without breaking down the formation at the shoe. If a shallow gas kick is taken while drilling top hole then the kick should be diverted. Drilling shallow sand too fast can result in large volumes of gas cut mud in the annulus and cause the well to flow, also fast drilling can load up the annulus increasing the mud density leading to lost...

Graph showing change in bottom hole pressure corresponding to surface drilling mud density when gas

If very fast penetration is made in a gas-bearing formation, the percentage of gas in the mud is likewise increased and problems may result. The rapid expansion of gas near the surface may cause 'belching' at the bell nipple with a loss of mud from the well and a consequent drop in the hydrostatic pressure. This may induce further 'belching' and lowering of the hydrostatic pressure. This may induce further 'belching' and lowering of the hydrostatic pressure to below that of the formation so...

Flow Rate Increase

Well Control System Offshore

When an influx is flowing into a well with normal circulation in progress, the total volume of material flowing out of the well increases. A flow sensor, such as a flow paddle system, provides a means for measuring quite small variations in flow See Figure 1 When a kick is occurring from relatively low permeability formations, as a slow 'bleed in', it is unlikely that any variation in flow rate will be observable. Roll, and more particularly, heave on a floating vessel will provide considerable...

Incorrect Hole Fill Volume

The importance of ensuring that the correct amount of mud is added to the hole to replace the drillstring as it is removed has already been discussed. Equally it is important to ensure that the correct amount of mud returns from the hole as the drillstring is run back. Careful monitoring of trip tank volumes, or hole fill up volumes, is essential. If serious doubt exists over a discrepancy, and re-calculation and level checks still show that a discrepancy may exist, the safest response is to...

Kick Tolerance Fixed Rig Simple Method

A Maximum kick length, or Volume at shut-in MAASP - SIDPP - Mud gradient - Influx gradient Length of influx at shut-in. now, Convert to a volume in barrels. b Convert the length calculated in a above into the volume at the annulus section below the casing shoe. Volume in barrels. c Use Boyles gas law to convert this to a volume in downhole conditions. Where P1 Formation breakdown pressure at shoe. V1 Volume calculated in b .

Drilling Break

A sudden increase in rate of penetration is usually caused by a change in formation type. It may however signal an increase in permeability and a loss of pressure overbalance. Both these effects result in faster drilling. The drilling break may be spectacular, though most commonly a gradual change is seen. It is rare for the drilling break to indicate a kick is in progress, though it is often a sign that conditions are changing and formation pressure rising, which may lead to a kick.

Hard Shutin Procedure Floating

1 When any indication is observed while drilling that the well maybe flowing, stop rotating the drill string with pumps running and space out for hang off rams. 2 Stop pumps and check for flow, if positive 3 With compensator at mid-stroke close annular or pipe rams. 4 Open fail-safe valves on the choke line. 5 Call supervisors and commence plotting a graph of shut in drill pipe pressure. Check pit volume again. 6 If rams have been closed then reduce manifold pressure, slack off on drill string...

Shale Density Cuttings

The examination of shale cuttings and or cores can provide information on formation pressures. Properties of shale such as bulk density, shale type, size, and shape can be related to abnormal pressures. Several techniques, such as the graduated density column method or the mud balance method, are available to measure the density of shale cuttings recovered at the shaker. Care must be exercised to separate bottom cuttings from upper hole cavings. Also, cuttings must be properly washed and or...

Using Riser PSCR vs Choke Line PSCR for Well Kill Calculations

Many people who work through Subsea Well Control calculation for the first time, often ask why the slow circulating pressure SCR through the riser is used, when the well is circulated through the choke line, and choke line slow circulating pressures is not included The following calculations are with the choke line friction losses included, this will show that the wellbore is going to be over pressurised by this choke line friction value. So adjustments must be made To enable the friction to be...

Ram Bops

Bop Shear Ram

Ram type BOPs are the most common type of blow out preventers. This section looks at three common types in use Shaffer 'SL', Cameron 'U' and Hydril 'V'. API RP53 requirements state that surface rams must close within 30 seconds. Subsea rams must close within 45 seconds. The Cameron 'U' BOP is a ram type preventer designed for both land and subsea operations. U BOP rams are pressure energising. Wellbore pressure acts on the ram to increase the sealing force and to maintain the seal in the event...

Pit Volume Increase

Any invasion of formation fluid must result in the expulsion of mud from the well, and this shows up as an increase in surface volume in what is, normally a closed circulating system. As is the case with flowrate, a gain in pit level may be hard, or impossible, to detect when a slow bleed-in of fluid occurs. It is also very easy for other factors to mask a change in pit level. Surface additions to the mud system, or surface withdrawals and dumpings, must be done with the Driller's knowledge....

Example Well Kill Calculation

This example is based upon the following situation Company policy is to keep the choke and kill lines full of seawater to avoid settling. A kick is taken and the well is correctly shut in and the pressures recorded. There is no Float in the string. The choke line pressure drop is known to be as follows with 13.0 ppg mud . 3.5 bbl min 450 psi The recorded slow circulating rates down the pipe and up the riser are 3.5 bbl min 800 psi

Annulars Hydril Gl Preventer

Well Control System Offshore

The 'GL' preventers are designed for both subsea and surface operations. Features of the 'GL' make it particularly useful for subsea and deepwater drilling. Secondary Chamber Balancing Chamber Figure 30 Hydril 'GL' Annular Preventer Secondary Chamber Balancing Chamber k Cutaway View of 'GL' BOP shown in Midstroke. 5,000 or 10,000 psi bottom connections are available in hib, API flanged, or studded connection. Figure 30 Hydril 'GL' Annular Preventer THE SECONDARY CHAMBER, which is unique to the...

Formation Fluid Pressure Pf

Sedimentary Process

The formation fluid pressure, or pore pressure, is the pressure exerted by the fluids within the formations being drilled. The sedimentary rocks, which are of primary importance in the search for, and development of oilfields, contain fluid due to their mode of formation. Most sedimentary rocks are formed as accumulations of rock debris or organic material, underwater. Since over two thirds of the earth's surface is covered with oceans, the vast majority of sedimentary rocks are laid down as...

Bottom Hole Pressure

The term 'bottom hole pressure', as used here, means the sum total of all pressures being exerted on a well by our operations. Bottom hole pressure is the sum of the hydrostatic pressures exerted by the fluids in the well, plus any circulating friction loss e.g. Annular Pressure Loss , plus any surface applied back pressures, where appropriate. This is the total pressure exerted by us. It is usually intended to at least balance the formation fluid pressures in the exposed portion of the well.

Auxiliary Well Control Equipment

Drill String Non Return Safety Valve

The Gray inside BOP is a heavy-duty drop check valve with a conical plug to reduce the cutting action of the mud on the valve seat, ensuring positive closure whenever required. Installed in the drill string, it protects the rotary swivel, rotary hose, standpipe, and mud pumps from drill pipe kicks. It may be used along with high-pressure pumps to maintain well control by preventing high-pressure backflow. A special release tool allows the valve to be held open to permit stabbing into position...

Drill Pipe Bop Installed

With the inside BOP now in the string, the shut in drill pipe pressure will have to be measured by pumping down the string very carefully until an increase in annular pressure is noted. When the pressures and pit gain have been recorded, a decision can be made to either strip the bit back to bottom or perform 'top kill'. This procedure has the disadvantage that with the string stripped to bottom and an inside BOP installed, wireline operations would be impossible in the event that the string...

RigtrAiim

Diverter Insert

Drilling amp Well Services Training Operating parameters is typically 750 psi closing pressure through 1-inch ID lines with a maximum wellbore pressure of 500 psi. Closing time is less than 10 seconds. Overboard lines should be as straight as possible in configuration to minimise erosion during diverting. Diverters can be connected directly to the conductor or drive-pipe or attached above the BOPs. On floating rigs the diverter is used to prevent trapped gas from reaching the rig floor after a...

Mud Gas Separator Poor Boy Degasser

Poor Boy Degasser

The height and diameter of an atmospheric separator are critical dimensions which affect the volume of gas and fluid the separator can efficiently handle. As the mud and gas mixture enters the separator, the operating pressure is atmospheric plus pressure due to friction in the gas vent line. The vertical distance for the inlet to the static fluid level allows time for additional gas break-out and provides an allowance for the fluid to rise somewhat during the operation to overcome friction...

Subsea Control Pods

Control Pods

The subsea control pods contain the equipment that provides the actual fluid transfer from the hose bundle to the subsea stack. A typical pod assembly See Figure 64, consists of three sections An upper female receptacle block permanently attached to the lower marine riser package A lower female receptacle permanently attached to the BOP stack. Control fluid enters the pod at the junction box and is routed either direct to an SPM valve or to one of the two regulators one for the BOP rams and one...

Shallow Gas Sands

Drilling into shallow gas pockets is one of the most dangerous situations that can be encountered. In a shallow well, gas can travel to the surface very rapidly, giving little warning. While drilling shallow hole, the short surface casing string is set in a relatively weak formation. It is normally necessary to divert the flow rather than shut the well in, risking fracture at the casing shoe and the possibility of gas coming up around the outside of the well. As the 'bottom-hole' times involved...

Annulars Cameron Dl

Cameron Annular Preventer Packer

Cameron annular blowout preventers are available in bore sizes from 7 V16 to 21 and in pressure ratings to 20,000 psi. The packer is able to contain full rated working pressure even after long periods of use. Packer replacement is simple and fast. The quick release top, with its one-piece split lock ring, permits quick packer change out with no loose parts involved. The annular is designed to simplify field maintenance. Components subject to wear are replaceable in the field. The entire...

Swabbing In A Kick

Swabbing Well

When the drillstring is pulled up out of the hole during a trip, mud must flow down past it to fill the space left behind. Energy is needed to make the mud move, and this is shown as a pressure drop as the mud flows a reverse 'annulus pressure loss'. The effect is that the total pressure exerted by the fluid column is reduced slightly. The effect of the bit and bottom hole assembly can be compared with a loosely fitted plunger in a syringe. Since the pressure drop is related to the energy...

Stripping

Rig Well Test Manifold

See Figure 1 to Figure 7 1.2.1 General Stripping is an emergency well control procedure. It requires good planning, proper training The primary objective of the stripping operation shall be to maintain a constant bottom hole pressure, thus preventing a build up of excessive borehole pressures or influx from exposed The following are guidelines for carrying out a successful stripping operation a Pressure control is based on a volume balance. This means that for every barrel of pipe stripped in...

Lost Circulation

Mud Losses

Kicks can occur when total lost circulation occurs. If the loss of whole mud to natural or artificially induced fractures is sufficiently great, then all returns from the well will cease and the level of mud in the well annulus will drop. Loss of circulation can occur to cavernous or vugular formations naturally fractured, pressure depleted or sub-normally pressured zones fractures induced by excessive pipe running speeds annulus plugging due to BHA balling or sloughing shales excessively high...

Hydril Packing Units Selection

Well Control With Oil Based Mud

Natural rubber is compounded for drilling with water based drilling fluids. Natural rubber can be used at operating temperatures between 30 F to 225 F. When properly applied, the compounded natural rubber-packing unit will usually provide the longest service life. Nitrile rubber a synthetic compound is for use with oil based or oil additive drilling fluids. It provides best service with oil-based muds, when operated at temperatures between 20OF to 190OF. Neoprene rubber is for low temperature...

Other Kill Methods

Where a gas kick is taken into a well, and the pipe has been fully tripped out of the hole, a problem arises. Gas shut in will slowly migrate through the mud, and if not allowed to expand, will retain its pressure and bring this up the hole. Casing pressure, and bottom hole pressure, will steadily rise until damage occurs. In many cases, drillpipe is stripped in to allow circulation to be effected. In general this can be done more rapidly than the gas can migrate. It is usually preferred and is...

SPM Valves

Valve Well

As described above these valves direct the regulated power fluid to the desired side of the preventer, valve or connector operating piston and vent the fluid from the other side of the piston to the sea. The annular preventers typically use large 1 V2 SPM valves in order to provide sufficient fluid flow, the ram preventers use 1 valves and the other functions such as failsafe valves and connectors use valves. Figure 65 shows an example SPM valve. rilling S Well Services Training The valve is a...