Effect Of Porosity

Thus, 10 bbl of formation solids arrive at the surface. However, consider drilling 10 bbl of hole. Ground rock occupies the same volume as the rock before it is drilled. If a drilled formation has a 10 pore volume, or porosity, the rock added is 9 bbl and the volume of fluid in the pore space is 1 bbl. If the fluid in the pore space is liquid, no volume change will occur when the formation is ground into small pieces and enters the drilling fluid. The pit levels remain constant except for the...

Centrifuges And Gas Cutting

The centrifuge feed is typically a Moyno pump, also called a progressing cavity pump. The Moyno pump is a positive displacement pump and does not gas-lock, as does a centrifugal pump, but the input feed is reduced. The reduction is in direct proportion to the gas in the mud and the feed pressure to the centrifuge. The gas at atmospheric pressure in the mud is compressed by the Moyno pump to the feed pressure. The compression of the gas reduces the output of the pump (Box 9.2). Reduction in feed...

Estimating The Ratio Of Lowgravity Solids Volume And Barite Volume In Mud Cleaner Screen Discard

An estimate of the low-gravity solids content of the mud cleaner screen discard can be made by weighing the discard. Since the solids concentration will be around 60 volume, the mud weight will be a reasonable predictor of the low-gravity solids concentration. For low-gravity solids with a specific gravity (SG) of 2.6 and a barite SG of 4.2, the equation to determine the low-gravity solids concentration, VLG, is where Vs is the volume percentage of total suspended solids, and MW is the mud...

Conventional Polymers

Highly shear-thinning polymers that are used to provide high viscosity at very low shear rates (e.g., xanthan gum) can be expected to affect the performance of low-shear-rate solids-control devices, such as settling tanks, hydrocyclones, and centrifuges. If these polymers exhibit visco-elasticity, the elastic nature of the polymers at low shear rates may reduce efficiency of these low-shear-rate devices even more. Extensional effects (see the Section 2.3), which can produce a different kind of...

Ambient Temperature

The National Electrical Manufacturers Association (NEMA) full-load motor ratings are based on an ambient temperature of 40 C (104 F), at a EFFECT OF VOLTAGE VARIATION ON INDUCTION MOTOR CHARACTERISTICS EFFECT OF VOLTAGE UNBALANCE ON MOTOR PERFORMANCE -15 -10 -5 0 +5 +10 +15 PERCENT VOLTAGE VARIATION MOTOR UTILIZATION (NAMEPLATE) VOLTAGE, VOLTS When the line voltages applied to a polyphase induction motor are not equal, unbalanced currents in the stator windings will result. A small percentage...

Example

For the case of the 80 removal efficiency, 229 bbl of drilled solids and drilling fluid will be discharged (Figure 15.3). Although this is only 21 bbl less than the 90 removal efficiency, the dilution volumes are significantly higher. The dilution of the 20 bbl of returned drilled solids to a 4 vol level requires the addition of 480 bbl 20 bbl 0.04 to the system. The reconstituted 500 bbl of drilling fluid will contain 20 bbl of drilled solids and 480 bbl of clean drilling fluid. Since only 229...

Excess Drilling Fluid Built

Normal discards from fine screens on linear motion shale shakers and from hydrocyclones contain about 35 vol solids, as shown in Figure 15.6. If all of these are drilled solids, the volume of drilling fluid discarded with the drilled solids can be calculated. The statement that the volume of discarded solids is equal to 35 of the discarded volume can be written 0.35(volume of fluid discarded with drilled solids) 204 bbl (0.35)(volume of total fluid discarded with drilled solids) volume...

Fluid Rheological Properties

Literature indicates that the liquid capacity of a shale shaker screen decreases as the plastic viscosity (PV) of a drilling fluid increases. PV is the viscosity that the fluid possesses at an infinite shear rate.1 Drilling-fluid viscosity is usually dependent on the shear rate applied to the fluid. The shear rate through a shale shaker screen depends on the opening size and how fast the fluid is moving relative to the shaker 1The Bingham Plastic rheological model may be represented by the...

General Comments

Exercise 1 assumed that the clean drilling fluid volume was known. Frequently, drilling fluid is not metered into the pits, but the new fluid is built by adding liquid and solids to the tanks to keep the pit levels constant and maintain the drilled-solids concentration at some target value. Since the barite concentration in the drilling fluid was also kept at the same value, 9.5 vol, it has been used as a tracer to determine how much clean drilling fluid was added. In Exercise 1, the dilution...

Hazardous Locations

Construction and installation of all electrical equipment placed in a flammable or potentially explosive location must receive careful consideration. In some drilling and production sites where the occurrence of explosive mixtures of flammable materials and air cannot be prevented, special construction measures for prevention and or containment of ignition sources are warranted. Such areas are classified by hazardous ratings, which will be discussed later in this chapter. Hazardous locations...

Health Safety And Environment And Waste Management

2.6.1 Handling Drilling Fluid Products and Cuttings Working with drilling fluids can be hazardous. Some drilling-fluid products emit noxious or hazardous vapors that may reach levels that exceed the maximum recommended short-term or long-term safe exposure limits. Some shale and corrosion inhibitors and some oil-base mud emulsifiers tend to produce ammonia or other hazardous volatile amines, particularly in hot areas on a rig. Other products are flammable or combustible (flash point < 140 F),...

Heavy Drilling Fluids

Various arbitrary procedures seem to be developed by operating personnel in the field. Often a centrifuge is run for a specific number of hours per day, or a hydrocyclone bank is used for only a short period. Mud cleaners seem to also attract a variety of erroneous rules of thumb. In heavily weighted drilling fluids, above 13-14 ppg, mud cleaners are frequently shut off because of excessive barite discards. When a mud tank system is plumbed incorrectly, specifically when mud guns transport...

Hole Cleaning

Good solids control begins with good hole cleaning. One of the primary functions of the drilling fluid is to bring drilled cuttings to the surface in a state that enables the drilling-fluid processing equipment to remove them with ease. To achieve this end, quick and efficient removal of cuttings is essential. In aqueous-based fluids, when drilled solids become too small to be removed by the solids-control equipment, they are recirculated downhole and dispersed further by a combination of...

How A Shale Shaker Screens Fluid

The primary purpose of a shale shaker is to remove as many drilled solids as possible without removing excessive amounts of drilling fluid. These dual objectives require that cuttings (or drilled solids) convey off the screen while simultaneously most of the drilling fluid is separated and removed from the cuttings. Frequently, the only stated objective of a shale shaker is to remove the maximum quantity of drilled solids. Stopping a shale shaker is the simplest way to remove the largest...

Inaccuracy in Calculating Discard Volumes

The volume of discard was either 200 bbl or 180 bbl. In either case the discard tanks had to contain 59.3 bbl of drilled solids that came to the surface from the drilling operation. In one case, the drilled-solids concentration of newly drilled solids in the discard would be 59.3 bbl 200 bbl, or 29.7 vol. In the other, it would be 59.3 bbl 180 bbl, or 33.9 vol. In the 200-bbl case, 141 bbl of good drilling fluid were discarded and in the 180-bbl case, 121 bbl of good drilling fluid were...

Injection

Injection involves making a suitable slurry out of the waste generated during drilling operations. This solids-laden slurry is pumped into the formation at pressures exceeding the fracture. Since this is the only disposal method not involving the surface or the sea bottom, waste streams that would be undesirable to surface-dispose of could be safely disposed of by injection. However, in the United States, only exempt waste can be injected. Nonexempt waste must be taken to an appropriate and...

Installation

Low places in the flowline will trap cuttings. Flowline angle should be such that settling of solids does not occur, that is, a 1-inch drop for every 10 feet of flowline seems to be a good rule of thumb. 2. When a back tank (possum belly), is used, the flowline should enter at the bottom to prevent solids from settling and building up. If the flowline enters over the top, it should be extended to within one pipe diameter of the flowline from the bottom. 3. Rig up with sufficient space and...

Integral Unit with a Single Vibratory Motion

Typically, this device uses a linear motion shaker and incorporates a scalping screen in the upper part of the basket. The lower bed consists of a fine-screen, flowline shaker unit, and the upper scalper section is designed with a smaller-width bed using a coarser screen. Compared with the other cascade shaker units, this design significantly lowers the weir height of the drilling-fluid inlet to the upper screening area. Visibility of and access to the...

Integral Unit with Multiple Vibratory Motions

This design type combines the two units of the separate system into a single, integral unit mounted on a single skid. Commonly, a circular, elliptical, or linear motion shaker is mounted above a linear motion shaker on a common skid (Figure 7.19). The main advantages of this design are reduced installation costs and space requirements. The internal flowline eliminates the manifold and piping needed for the two separate units. This design reduces screen visibility and accessibility to the drive...

Introduction To Electromagnetic Theory

Current flow in a conductor causes a magnetic field to form around the conductor. The right-hand rule states that pointing the right thumb toward the direction of current flow causes the fingers to show the direction of the magnetic field. In a DC circuit, current flows out the positive terminal and into the negative terminal. A bar magnet has two poles a north pole and a south pole. Invisible magnetic lines of flux exit one pole and enter the other pole. The magnetic field, defined by the...

Laboratory Analysis

The required laboratory work consists of determining the weight percentage of suspended solids in the samples. With water-based samples, the simplest method is to determine the weight of the sample using a precise analytical balance, remove the water by dehydration at 200 F in an oven, and weigh the remaining solids. Correction factors should be determined and applied in cases in which the base liquid contains more than 10,000 ppm salt, or emulsified oil. Determining Percentage of Suspended...

Leon Robinson

Shale shaker is a general term for a vibrating device used to screen solids from a circulating drilling fluid Many configurations have been used. These include A square or rectangular screening area with drilling-fluid flow down the length Revolving, nonvibrating, cylindrical screens with longitudinal flow down the center axis Circular screens with flow from the center to the outside Other configurations have been tried but have not become commercial. The majority of shale shakers flow the...

Mark C Morgan

The purpose of a drilling rig surface fluid processing system is to provide a sufficient volume of properly treated drilling fluid for drilling operations. The active system should have enough volume of properly conditioned drilling fluid above the suction and equalization lines to keep the well bore full during wet trips. The surface system needs to have the capability to keep up with the volume-building needs while drilling otherwise, advanced planning and premixing of reserve mud should be...

Motors For Hazardous Duty

A summary of hazardous-location designations as outlined in the U.S. National Electrical Code is given in Table 17.7. IEC standards that address equipment for use in explosive atmospheres are contained in a series of Publications 79-0 through 79-10. Hazardous (Classified) Location Reference Guide (specification must include class, division, and group) Hazardous (Classified) Location Reference Guide (specification must include class, division, and group) Areas containing flammable gas or vapor...

Mud Hopper Recommendations

The following recommendations will promote efficient mud hopper installation and use Select a mud hopper that is properly sized for the mud system. Generally, a single hopper is sufficient for most rigs. If the mud circulating rate is greater than 1200 gpm ( 4550 lpm), then consider using a hopper with 1200-gpm capacity. Generally, there is no need to add chemicals faster than this. For many operations, 600 to 800 gpm ( 2270 to 3030 lpm) is adequate. Keep the lines to and from the hopper as...

Nature of Drilled Solids and Solid Additives

Particle size, density, shape, and concentration affect virtually every piece of equipment used to separate drilled solids and or weighting material from the drilling fluid. In the theoretically perfect well, drilled solids reach the surface with the same shape and size that they had when they were created at the drill bit. In reality, cuttings are degraded by physicochemical interaction with the fluid and mechanical interaction with other cuttings, the drill string, and the well bore. Cuttings...

Nature Of Drilling Waste

It is obvious, from the preceding discussion, that drilling waste contains a large amount of base fluid, whether that fluid is diesel oil, mineral oil, olefin, ester, or water. A more detailed discussion about the nature or characteristics of the waste should consider the place of disposal. In a broad sense, this can be accomplished by considering that all waste must be disposed in the water, on land, or in the air. For example, the characteristics of drilling waste when discharged offshore...

Nonoilfield Drilling Uses Of Shale Shakers

Trenchless drilling is one of the fastest growing areas for shale shaker use other than in drilling oil and gas wells. Many of these shakers are used in conjunction with hydrocyclones, creating a mud cleaner. Microtunneling has become very popular in Europe and is being used more and more in the United States. Microtunneling is horizontal boring of a large-diameter hole (from 27 inches up to 10 feet) while simultaneously laying pipe. This is typically done in cities for laying or replacing...

Nonoilfield Use Of Mud Cleaners

One use of mud cleaners that has been very profitable has been in microtunneling. Tunneling under roadways, lakes, or streams for pipelines, fiber-optic conduits, or other installations requires drilling with a circulating fluid. Frequently, the liquid is difficult to acquire and disposal is a problem. So these small drilling systems install a mud cleaner on top of a one-tank circulating system. The solids from the mud cleaner screen are removed, and the excess liquid is returned to the tank....

Operating Guidelines

Shale shakers should run continuously while circulating. Cuttings cannot be removed if the shaker is not in motion 1. Drilling fluid should cover most of the screen. If the drilling fluid covers only one fourth or one third of the screen, the screen is too coarse. 2. A screen with a hole in it should be repaired or replaced at once. Holes in panel screens can be plugged. Install screens according to manufacturer's recommended installation procedures. Cuttings are not removed from the drilling...

Operating Mud Cleaners

When the first mud cleaners were introduced into the field, they had to be shut off during weight-up. A significant amount of barite was discarded during the first circulation. Actually, this revealed that the mud tanks were plumbed improperly. Drilling fluid was frequently pumped through mud guns from the additions or suction section back upstream to the removal tank. Barite can meet American Petroleum Institute (API) specifications and still have a large amount that will be removed with an...

Operation

For double-deck shale shakers, run a coarser-mesh screen on the top deck and a finer-mesh screen on the bottom. The coarser screen should be at least two API sizes coarser than the finer-mesh screen. Watch for a torn bottom screen. During normal drilling operations, cover at least 75-80 of the bottom screen with drilling fluid to maximize utilization of available screen area. Properly designed flowback pans may improve shaker performance. (Gumbo shakers mounted above as an integral part of...

Points About Separators And Separation

Following are points about liquid gas separation. Gas and water in a mixture with no solids or emulsifiers separate naturally and quickly by gravity because gas is lighter, floats up in big bubbles, and breaks out. Water and oil in a mixture with no solids or emulsifiers separate naturally by gravity because oil is normally lighter than water. Bear in mind, however, that some oil is heavier than water and that some oil is soluble in water (and all gas is soluble in oil). Gas and oil may require...

Preface

In the early 1970s, the International Association of Drilling Contractors (IADC) formed a committee to study solids control on drilling rigs. After 10 years of work, we published the IADC Mud Equipment Manual. The committee started with only six members and ended with about 27. Many members remained on the committee when they changed employers, and employers wanted to stay represented and active on the committee. Others heard about our work and asked to join. The 11 handbooks in the Mud...

Pros And Cons Of Agitation Equipment

Many rigs use a combination of agitators and mud guns. To summarize the preceding discussions on mechanical agitators and mud guns, a list of pros and cons are presented to aid in the proper selection and application of agitation equipment. The list is not necessarily complete but will help both the designer and rig personnel consider both immediate and long-term consequences of decisions. Mechanical agitators may be supplemented with mud guns strategically located to stir dead zones. Round...

Quantifying Drilling Waste

Drilling waste consists of waste drilling fluid, drilled cuttings with associated drilling fluid, and, to a lesser extent, miscellaneous fluids such as excess cement, spacers, and a variety of other fluids. The amount of drilling waste depends on a number of factors. These include hole size, solids-control efficiency, the ability of the drilling fluid to tolerate solids, the ability of the drilling fluid to inhibit degradation or dispersion of drilled cuttings, and the amount of drilling fluid...

Quantity of Solids

Solids compete with the liquid for openings in the shaker screen. Fast drilling can produce large quantities of solids. This usually requires coarser screens to allow most of the drilling fluid to be recovered by the shale shaker. Fast drilling is usually associated with shallow drilling. The usual procedure is to start with coarser-mesh screens in the fast drilling, larger holes near the top of the well and to ''screen down'' to finer screens as the well gets deeper. Finer screens can be used...

Question

Rental, mobilization, and demobilization costs for 10 days' use totals 7500. At a total of 15 bbl for each new barrel of fluid mixed, the breakeven point on the use of the centrifuge is reached when the new mud prepared is reduced by 500 bbl ( 7500 15 bbl). Inasmuch as each bbl of incorporated solids requires the preparation of 32.33 bbl of new fluid to be added to each bbl of incorporated solids, the removal of each bbl of drilled solids reduces the new mud volume by 33.33 bbl. To reduce the...

Drilling Fluid References

Web site www.burgess-mfg.com. Brochure ''Burgess Magna-VacTM Degassers.'' Personal conversation with Harry Burgess, 8 11 03. Derrick Equipment. Web site www.derrickequipment.com products vacu_ flo.htm Goins & O'Brien, Blow Out Control and What You Need to Know About It. Series from Oil & Gas Journal, 1960. Lawson, G. & Liljestrand, W. Mud Equipment Manual Handbook 5, Degassers. Gulf Publishing, 1976. Rehm, WA. Practical Underbalance Drilling and Workover....

Screen Cloths

Shale shakers remove solids by processing solids-laden drilling fluid over the surface of a vibrating screen. Particles smaller than the screen openings pass through the screen along with the liquid phase of the drilling fluid. Larger particles are separated into the shaker overflow for discard. The shaker screen acts as a 'go no-go' gauge. That is, particles larger than the screen openings remain on the screen and are discarded. Particles finer than the screen openings go through the screen...

Selection of Shaker Screens

Some proprietary computer programs are available that reportedly allow predictions of screen sizes used on some shale shakers. Most of these computer programs have been verified with data taken from laboratory-prepared drilling fluid with limited property variation. Different drilling-fluid ingredients can reduce the capacity of a shaker system. For example, a drilling fluid containing starch is difficult to screen because starch, acting as a good filtration control additive, tends to plug...

Separate Unit

The separate unit system mounts usable rig shakers (elliptical or circular motion) on stands above newly installed linear motion shakers (Figure 7.18). Fluid from the rig shakers (or scalping shakers) is routed to the back tank of a linear motion shaker. Line size and potential head losses must be considered with this arrangement to avoid overflow and loss of drilling fluid. This design may reduce overall cost by utilizing existing equipment and, where space is available, has the advantages of...

Shaker Description

The majority of shale shakers use a back tank (commonly known as a possum belly or a mud box) to receive drilling fluid from the flowline (Figure 7.3). Drilling fluid flows over a weir and is evenly distributed to the screening surface, or deck. The screen(s) are mounted in a basket that vibrates to assist the throughput of drilling fluid and the movement of separated solids. The basket rests on vibration isolator members, such as helical springs, air springs, or rubber float mounts. The...

Shaker Development Summary

Shale shakers have undergone many improvements since the Shale Shaker Handbook was written in the early 1970s. The current design, linear motion shakers, was introduced in the 1980s and has become widely used because of its improved solids conveyance and fluid throughput. The various types of motions are discussed in the next sections. Linear motion has made it possible to move solids toward the discharge end of the deck while it is tilted uphill. The uphill tilt of the deck creates a pool of...

Shale Shaker Limits

A shale shaker's capacity has been reached when excessive amounts of drilling fluid (or drilling-fluid liquid phase) first begins discharging over the end of the shaker. The capacity is determined by the combination of two factors 1. The fluid limit is the maximum fluid flow rate that can be processed through the shaker screen. 2. The solids limit is the maximum amount of solids that can be conveyed off of the end of the shaker. The two limits are interrelated in that the amount of fluid that...

Shale Shakers And Gas Cutting

Shale shaker screening is dependent on a constant flow of drilling fluid with cuttings. The fluid must pass through the screen, and the cuttings must either pass through or be rejected by the screen. Gas cutting in the drilling mud can have up to three different effects that upset the screening process. 1. Gas heading can cause volume surges in the mud flow that exceed the ability of the screen to handle fluid flow. This is usually from gas, intermixed in the mud, rapidly expanding at the...

Sizing Agitators

Regardless of what style of agitator or impeller is used, proper sizing of components is critical. Once compartment size has been determined, the impeller diameter and corresponding horsepower requirements must Figure 10.11. Baffles pointed at corners note poor placement of pipe. Figure 10.11. Baffles pointed at corners note poor placement of pipe. be calculated. If the maximum mud weight to be used with the rig is not known, it is best to base all calculations on 20 lb gal fluid (2.4 specific...

Solids Removal Equipment Efficiency In An Unweighted Drilling Fluid From Field Data

Situation NoProfit Drilling Company is drilling 100 bbl of hole daily in a formation with 15 porosity. For four consecutive days, 400 bbl of discards and fluid were captured each day in discard tanks. The pit levels remained constant, but some drilling fluid was jetted to the reserve pits daily to keep the pits from overflowing. The unweighted drilling fluid weighed 9.4 ppg daily and contained 2 vol bentonite. Since no barite is contained in the drilling fluid, the volume of low-gravity solids...

Solids Type Size and Shape

The shape of solids frequently makes screening difficult. In single-layer screens, particles that are only slightly larger than the opening size can become wedged into openings. This effectively plugs the screen openings and decreases the open area available to pass fluid. Solids that tend to cling together, such as gumbo, are also difficult to screen. Particle size has a significant effect on both solids and liquid capacity. A very small increase in near-size particles usually results in a...

Sree

Equating the volume of clean drilling fluid needed to the volume of discard results in the minimum volume of clean drilling fluid needed and, as a consequence, the minimum volume of drilling fluid disposal. For that reason the resulting SREE required is called the optimum solids-removal efficiency. It is independent of the volume of drilled solids reaching the surface, or the volume of the drilling-fluid system. If the SREE is less than the value required to achieve the minimum volume, the...

Study Questions

234.5 111.3 C (winding temperature) A four-wire ohmmeter is used to negate the resistance of the equipment test leads. If a two-wire ohmmeter is used, the resistance of these leads must be accounted for. Technically, if one wanted to determine the winding temperature, this procedure is not correct. Although live winding test equipment is available (variation of a Wheatstone bridge), most motor temperature testing is still done with an ohmmeter. The winding temperature calculated above is...

Surface Active Materials

The surface-active additives in mud products are designed to adsorb on a specific type of substrate cuttings (shale inhibitors, antiaccretion agents, and oil wetting agents), weighting material and LCM (oil-wetting agents), liquid internal phase (emulsifiers), and drill string casing well bore (lubricants, ROP enhancers). However, none of these additives is perfectly selective for its designed target substrate and every one adsorbs on various types of surfaces. Lubricants and ROP enhancers, in...

Tank and Compartment Dimensions

Proper agitator sizing is based upon the amount of fluid to be stirred. Therefore, knowledge of tank dimensions is required. Under most circumstances, all compartments other than the sand trap require agitation. Some systems convert the sand trap to an active compartment in this case, agitation is required. This can be problematic, considering that many systems have shakers mounted above that compartment, with little or no space allotted for mechanical agitators. If such a contingency is...

The Use of Centrifuges with Unweighted Drilling Fluids

With properly designed and engineered unweighted muds, which have low total solids content, in which particle size is not a primary cause for concern, the objective of centrifuging is the removal of drilled solids. Massive dilution is required to compensate for the incorporation of these solids if their concentration is to be controlled at the low levels that are normally desired. Centrifuging, and separating the underflow, can remove significant quantities of otherwise inseparable solids. This...

The Use of Centrifuges with Weighted Drilling Fluids

With the unavoidably higher solids content of weighted muds, the increase of gel strengths and viscosities, as well as the degradation of filter cake quality associated with the diminution of particle size with time, can become a serious problem. The problem is caused by the increasing concentration of colloidal and near-colloidal particles that are too fine to be separated from the base fluid. Centrifuges are used to selectively remove these fine solids. In this application, the underflow is...

Transformers

The transformer is an inexpensive piece of stationary equipment that operates at a high efficiency. Transformers make it possible to generate energy at any level, say 20,000 volts, and transform it to energy at high voltage, such as 100,000 volts. Power lines transmit energy at high voltage to minimize losses. Power losses are proportional to the square of the current. At high transmission voltages, the current is low. Transformers are also used to transform energy at high voltage to energy at...

Solidification Stabilization

Solidification continues to be sold around the world as an inexpensive alternative treatment technique to other methods of waste management, particularly in countries with relatively lax environmental regulations. This treatment technique is not recommended unless a thorough investigation of the process to be used is conducted. Solidification (also referred to as encapsulation, fixation, and stabilization) is a technique in which material is added to reduce free water and possibly reduce or...

Motor Installation And Troubleshooting

When replacing a motor, its exact dimensions, as well as speed, hp, and torque characteristics should be determined and duplicated if the same performance is desired. When replacing a motor, the entire system should be inspected for internal and external degradation. Neither the motor mounting nor the mechanical coupling should exhibit signs of wear. The power supply and connections should not be damaged. These should be frequently checked for proper frequency, voltage, and voltage balance...

Diluting As A Means For Controlling Drilled Solids

One way that drilled solids can be kept at a manageable level is to simply dump some of the drilling fluid containing the drilled solids and replace it with clean drilling fluid. One half of the drilled solids is eliminated if one half of the system is dumped and replaced with clean fluid. Generally this is too expensive, so mechanical equipment is used. Traditionally, large volumes of drilling fluid were dumped from the system by aggressively dumping sand traps. This makes room available for...

Removal Efficiency

The term solids removal equipment efficiency is frequently used to describe solids-control equipment performance. This term may be somewhat confusing. American Petroleum Institute (API) Recommended Practice (RC) 13C, Solids Control,'' refers to the solids-removal process in terms of system performance. Solids-control equipment is designed to remove drilled solids, which are not dry when they are removed from the system. For example, the underflow discharge from a properly operating 4-inch...

Reasons For Drilledsolids Removal

Many years ago, a controversy raged concerning the effect of drilled solids on the cost of a well. Many thought that drilled solids were beneficial as an inexpensive substitute for weighting agents. As oil well drilling encountered more and more difficult conditions, hole problems finally became undeniably associated with excessive drilled solids. Frequently, production horizons near the surface were normally pressured and could be drilled with unweighted drilling fluids. Usually, these...

Cost of Removing Drilled Solids

Few wells can be drilled without removing drilled solids. However, even for 3000- to 4000-ft wells, one problem created by drilled solids, such as lost circulation, stuck pipe, or a well-control problem, will more than nullify the modest savings resulting from the decision not to properly process the drilling fluid. In expensive operations, the proper use of solids-removal equipment will significantly reduce drilling costs. Although drilled solids can be maintained by simply diluting the...

Selection Of Shale Shakers

Most drilling rigs are equipped with at least one shale shaker. The purpose of a shale shaker, as with all drilled-solids removal equipment, is to reduce drilling cost. Most drilling conditions require limiting the quantity and size of drilled solids in the drilling fluid. Shale shakers remove the largest drilled solids that reach the surface. These solids are the ones that can create many well-bore problems if they remain in the drilling fluid. Copper Wire Size Required to Limit Line Voltage...

Electric Motor Standards

Generally, standards for electric motors are based on those of NEMA, the International Electrotechnical Commission (IEC), and the Institute of Electrical and Electronic Engineers (IEEE). Most countries typically have their own standard or recognized standard. NEMA designs (A, B, C, D, and E) classify motors according to specific torque characteristics for effective startup and operation of equipment under particular loading and operating situations. Design B motors are commonly used on drilling...

Four Examples Of The Effect Of Solids Removal Equipment Efficiency

If the mechanical equipment does not remove a significant portion of the drilled solids reporting to the surface, it can become very expensive to maintain a reasonable level of undesirable drilled solids. Dilution, then, becomes a major portion of the solids-management strategy. Calculations indicate the performance of the solids-removal equipment. This set of calculations is simply a material balance of the volumes added and the volumes discarded. The calculations will be based on a...

Another Method Of Calculating The Dilution Quantity

The dilution required to compensate for the incorporation of 37.9 bbl of drilled solids was the 759 bbl of new mud, less the volume of the drilled solids in the new drilling fluid built, or 721 bbl. This is 19 bbl of dilution per bbl of incorporated solids (721.0 bbl 37.9 bbl). The calculation for the dilution, that is, the volume of new mud that must be prepared, is where V the volume of new mud (dilution) required, in bbl bbl of incorporated solids, and the concentration of drilled solids....

Conclusions

Hydrocyclones are simple, easily maintained mechanical devices without moving parts. Separation is accomplished by transfer of kinetic input or feed energy into centrifugal force inside the cone. The centrifugal force acts on the drilling fluid slurry to rapidly separate drilled solids and other solid particles in accordance with Stokes' law. The solids that are generated by drilling in some formations are too fine for shale shakers to remove. Hydrocyclones must be relied on to remove the...

Eugene Bouse

Consulting Engineer (Drilling Fluids, Solids Control, Drilling Waste Minimization) good measure of the effectiveness of the separation process. The capture equation is written f weight percentage of suspended solids in the feed u weight percentage of suspended solids in the underflow o weight percentage of suspended solids in the feed Capture analysis has not been widely used in the drilling-fluids solids-control industry for two reasons first, the need for representative samples precludes...

Removal Section

Undesirable drilled solids and gas are removed in this section before new additions are made to the fluid system. Drilled solids create poor fluid properties and cause many of the costly problems associated with drilling wells. Excessive drilled solids can cause stuck drill pipe, bad primary cement jobs, or high surge and swab pressures, which can result in lost circulation and or well-control problems. Each well and each type of drilling fluid has a different tolerance for drilled solids. Each...

Enclosure And Frame Designations

Motors operate best in areas free of airborne particles and corrosives and should have sufficient cool airflow to dissipate heat developed during operation. Poor ventilation causes many industrial motor failures. Motors should also be protected or shielded from damage by liquids. Rarely, if ever, do all these conditions exist. NEMA has defined various enclosures suitable for different operating environments. A list of these is given in Sidebar 3. Sidebar 3 Widely Used Electric-Motor Enclosures...

Vibrating Systems

The type of motion imparted to the shaker depends on the location, orientation, and number of vibrators used. In all cases, the correct direction of rotation must be verified. Unbalanced elliptical motion shakers use a single vibrator mounted above the shaker's center of gravity. Integral vibrators, enclosed vibrators, and belt-driven vibrators are used for this shaker design. Circular motion shakers use a single vibrator mounted at the shale shaker's center of gravity. Belt-driven vibrators...

Estimating Solids Removal Equipment Efficiency For A Weighted Drilling Fluid

After drilling 1000 ft of hole with a 12.5-lb gal drilling fluid circulated at 25 bbl min, the hole was circulated clean. This required four hole volumes to eliminate all solids in the discard. Assuming that the formation averaged about 13 vol porosity, a multiarmed caliper indicated that a volume of 97.3 bbl of new hole was drilled. The drilling fluid was freshwater-based mud weighted with barite and contained 2 vol bentonite, no oil, and 5 vol drilled solids. While drilling this interval,...

Gearbox

There are many types of gear reduction suitable for use with mechanical agitators. Most units fall into two categories worm roller type or helical bevel type. There is no direct evidence that one type is superior to the other, although most experts agree that helical bevel requires less horsepower, and it is therefore offered for larger applications over worm roller. Worm roller types are usually offered in right-angle drive with a single reduction in speed. Helical bevel gearboxes may be...

Location Of Mud Cleaners In A Drillingfluid System

Mud cleaners are normally positioned in the same location as desilters in a drilling-fluid system. Frequently, the desilters, or hydrocyclones, are used in the unweighted portion of a borehole by diverting the underflow away from the mud tanks. When a weighting agent, barite or hematite, is added to the system, screens are placed on the mud cleaner shakers. Solids discarded from the hydrocyclones are sieved to discard solids mostly larger than barite and return solids smaller than the screen...

Bernoullis Principle

The Bernoulli principle, first formulated by Daniel Bernoulli in 1738, is one means of expressing Newton's second law of physics, concerning conservation of energy. Roughly stated, this principle demonstrates that the sum of pressure and velocity through or over a device represents is equal, neglecting the effects of losses due to friction and or increases by adding energy with external devices such as pumps. The basic concept of Bernoulli's principle can be observed in routine daily activities...

Macropolymers

Large solids, such as those typically used as LCM, have irregular shapes that are generally classified as flake, fiber, or granule. These are usually removed at the shakers and discarded along with the cuttings. Treatment of whole mud with LCM rather than 100-bbl pill or slug requires reintroduction of fresh LCM into the circulating system before pumping it back downhole. At low concentrations 2 to 15 ppb , LCM tends to have little effect on standard mud properties. However, at higher...

Drilling Fluids Solids

Commercial solids are used in drilling fluids to provide desired density, viscosity, and filtration control. Additional drilled and sloughed solids become part of the fluid during the drilling process. These formation solids, as well as colloidal barite particles, when present in excessive concentrations, are detrimental to drilling-fluid performance and are considered to be contaminants. The coarser solids, though they can be troublesome, are ordinarily the least injurious to drilling-fluid...

Degasser Suction and Discharge

For proper operation of a vacuum-type degasser, the suction pit should be the first pit after the sand trap, or if no sand trap is present, then the first pit. This pit should typically be agitated in order to help roll the drilling fluid and break out as much gas, if present, as possible. The processed fluid flows into the next pit downstream. There needs to be a high equalizer or weir between these two tanks. The degasser discharge pit is also the suction pit for the centrifugal pump used to...

Active System Suction and Testing Section

The suction and testing section is the last part of the surface system. Most of the usable surface volume should be available in this section. Processed and treated fluid is available for various evaluation and analysis procedures just prior to the fluid recirculating downhole. This section should be mixed, blended, and well stirred. Sufficient residence time should be allowed so that changes in drilling-fluid properties may be made before the fluid is pumped downhole. Vortex patterns from...

Other Shearing Devices

Like the mud hopper, a number of devices are available to increase shear, speed hydration, and enhance curing and saturation. Prehydrating has several advantages that it improves the efficiency of addition, thus reducing over- or under-treatment. Overtreating may force dilution and the possible removal of excess fluid to make room for the increased fluid volume. Under-treating will hinder fluid performance reduces water loss to the formation by enhancing filter cake properties prevents...

Reserve Tanks

The reserve tank s are for storage of excess drilling fluid, base fluids, or premixed drilling fluid for future mixing additions. It could even be a completely different type of mud system for displacing the existing drilling fluid. Land drilling rigs do not have reserve tanks in their systems. Extra tanks are rented as needed for their operation. These tanks are typically called fractionalization frac tanks. Marine drilling rigs incorporate reserve or storage tanks in their design. The volume...

Impeller

Impeller Open Semi Closed

Centrifugal pumps are often referred to as kinetic energy machines. Rotation of the impeller causes fluid within the impeller to rotate at a high velocity, imparting kinetic energy to the fluid. This concept is described mathematically by the equation Hi theoretical head developed by the centrifugal pump, in ft u2 rotational velocity of the impeller at the outer diameter, in ft sec cu2 rotational velocity of the fluid as it leaves the impeller, in ft sec g gravitational constant, in ft sec2....

Shale Shaker Design

The purpose of a shale shaker is to induce drilling fluid to flow through a screen, transport solids across a screen surface, and discharge solids off the end of the screen. Its primary function is to remove drilled solids, which is the primary function of all solids-removal equipment. Screening is the result of using the energy developed by a rotating eccentric mass and applying that force to a porous surface. The energy causes the screen to vibrate in a fixed orbit or path. The elements of...

Sand Traps

Drilling Mud Centrifuge

After the drilling fluid passes through the main shaker, it enters the mud pit system. When screens 80-mesh and coarser were routinely used, the sand trap performed a very useful function. Large, sand-size particles would settle and could be dumped overboard. The bottom of a sand trap IFlowline Jl1 J_ Trap Screened Solids Dump Discard Solids I Screen Discard Underflow return Figure 5.5. Weighted mud two-stage centrifuging. Weighed Mud Single-Stage Centrifuging Weighed Mud Single-Stage...

Shape of Motion

Circular Motion Shale Shaker

Historically, the progression of the design of shale shakers has been toward allowing the use of finer screens. Shale shakers have developed through the years from relatively simple, uncomplicated designs to today's complex models. In fact, this evolutionary process has seen several distinct eras of shale shaker technology and performance. These developmental time frames can be divided into four main categories 1. Unbalanced elliptical motion The eras of oilfield shaker and screening...

Colloidal and Fine Solids

Clay solids e.g., bentonite, attapulgite along with clay-laden drilled solids, weighting material, and fine grades of bridging material e.g., limestone, CaCO3 will all affect the viscosity of a drilling fluid at moderate to high shear rates, thereby increasing the retention of drilling fluid on solids. Although elevated low-shear-rate viscosity is beneficial in many ways improved hole cleaning, etc. , nothing is gained by having elevated high-shear-rate viscosity. Thinners are often used in...

Low Pressure Mud Guns

Low-pressure mud guns usually require about 75 feet of head for effective operation see chapter 18 for head and pump sizing . Nozzle sizes range from V2 to 1 inch 12.7 to 25.4 mm . Centrifugal pumps pressurize the nozzles through standard wall piping typically schedule-40 pipe is used . The low-pressure system does not require heavy-walled piping. Because of higher flow rates, larger-diameter pipe is used to prevent excess friction loss. The jet nozzles are larger than in the high-pressure...

Cascade Systems Summary

Cascade systems use two sets of shakers one to scalp large solids gumbo and another to remove fine solids. Their application is primarily during fast, top-hole drilling or in gumbo formations. This system was designed to handle high solids loading. High solids loading occurs during rapid drilling of a large-diameter hole or when gumbo arrives at the surface. The introduction of high-performance linear motion and balanced elliptical shale shakers has allowed development of fine-screen cascade...

Suction

All compartments in this section require proper agitation. This section contains the tank s and or compartment s from which the rig pumps take suction, including any associated pumps such as charging pumps used to deliver fluid to the well or trip tank. Usually included is a pill slug compartment. The pill slug tank is used to prepare a drilling fluid with a higher density or extra hole-sweeping ability than usual generally a 20- to 50-bbl volume is sufficient. The denser nature of the fluid...

Surface Tanks

Most steel pits for drilling fluid are square or rectangular with flat bottoms. Each tank should have adequate agitation except for settling tanks. Additionally, each tank should have enough surface area to allow entrained air to leave the drilling fluid. A rule of thumb for calculating the minimum active surface pit area is For example, if the active circulating rate is 650 gpm, the surface area of each active compartment should be about 16 square feet. The depth of a tank is a function of the...

Trip Tank

A trip tank should also be a component of the tank system. This tank should have a well-calibrated, liquid-level gauge to measure the volume of drilling fluid entering or leaving the tank. The volume of fluid that replaces the volume of drill string is normally monitored on trips to make certain that formation fluids are not entering the well bore. When one barrel of steel drill string is removed from the borehole, one barrel of drilling fluid should replace it to maintain a constant liquid...

Power Systems

4g's 0.35 stroke at 900 rpm 4g's 0.20 stroke at 1200 rpm 4g's 0.13 stroke at 1500 rpm 4g's 0.09 stroke at 1800 rpm The most common power source for shale shakers is the rig electrical power generator system. The rig power supply should provide constant voltage and frequency to all electrical components on the rig. Most drilling rigs generate 460 alternating-current-volt VAC , 60 Hz, 3-phase power or 380 VAC, 50 Hz, 3-phase power. Other common voltages are 230 VAC, 190 VAC, and 575 VAC. Through...

Turnover Rate TOR

Impeller sizes are determined by calculating the TOR sometimes called time of rollover for each compartment. This is the time, in seconds, required to completely move the fluid in a compartment Table 10.1 and can be calculated by knowing the tank volume and impeller displacement Vt tank volume, in gallons or liters D impeller displacement, in gpm or lpm as displayed in Table 10.2 . For flat and canted impeller applications, TOR should range between 40 and 85 seconds. As the TOR approaches 40...

Drilling Fluid Excersises

This exercise demonstrates the effect of a slight increase in the drilled-solids concentration If the 80 removal efficiency were achieved and a 6 vol drilled-solids level would not create hole problems, another significant cost reduction is possible. With 80 removal efficiency and 1143 bbl of drilled solids reporting to the surface, 914 bbl would be discarded and 229 bbl returned to the pits. The drilling fluid needed to dilute the 229 bbl to 6 vol would require adding 229 bbl 0.06 , or 3817...

Separation Curves and Cut Points

Solids-separation performance is often described using cut points. The cut point is the size at which a stipulated percentage of the feed solids are separated. If a percentage is not stated, it is usually assumed to be 50 . For example, if a shale shaker is removing 50 of the 1001 particles and 50 remain in the mud, the D50 cut point is said to be 1001. If it is removing 90 of the 1201 particles, its D90 cut point is 1201. Figures 13.8 and 13.9 indicate the importance of this concept and also...

Median D Cut Points

In spray discharge, for any set of cone diameter, feed slurry compositions, flow properties, volumetric flow rates, and pressure conditions, some particles' size mass is 100 discarded from the apex. For every size and design of cone operating at a given pressure with feed slurry of a given viscosity, density, and solids distribution, there is a certain size mass of particle that shows no preference for either top or bottom discharge. As a result, 50 of this particular size exits through the...

Properties Of Drilling Fluids

Rheology Drilling Mud

Just as the nature of drilling-fluid solids affects the efficiency of solids-control equipment, the nature of the solids also plays an integral role in the properties of drilling fluids, which in turn affect the properties of the solids and the performance of the equipment. This intricate and very complex dynamic relationship among the solids, drilling fluid, and solids-control equipment is represented in Figure 2.7. Any change made to one of these affects the other two, and those in turn...

Bulk Addition Systems

Dry Mix Hopper Driling Fluids

A variety of systems are available to transport and contain large volumes of dry bulk chemicals. Commonly known as P-tanks pressure tanks , these vessels are usually mounted upright and connected via piping to a mud mixing hopper. They may also be mounted remote from the Figure 10.22. Specialized shearing pump. Figure 10.22. Specialized shearing pump. hopper and deliver material through a piping system by pneumatic force. Other designs mount the tanks above the hopper and gravity-feed the...

Mud Gun Placement

Tank Mixing Eductor

Mud guns are usually placed about 6 inches 15 cm from the tank bottom and typically come with a 360 swivel that allows directional positioning to stir dead spots. Dead spots can occur in right-angle compartments that have inadequate mechanical agitation or can be caused by piping or other mechanical obstructions. It is generally accepted that low-pressure nozzles are effective within a 5- to 9-feet diameter depending on the mud weight, viscosity, and nozzle velocity. Nozzle size and feed...

Historical Perspective

Drilled-solids management has evolved over the years as drilling has become more challenging and environmental concerns have become paramount. Equipment changes and improvements have responded to the necessity to treat more and more expensive drilling fluids. In this context, probably the largest impact on the drilling industry has been the recognition that polymers can make much better drilling fluids than those used heretofore even though they are expensive. Polymer drilling fluids require...