Flow Line to the

The flow line to the standpipe of the drilling rig acts as a manifold collecting the compressed air outputs from the primaries. These flow lines are API 2 7 8 inch OD , or 3 1 2 inch OD steel line pipe or ASME equivalent 5 . The valves in the flow line at the booster compressor allow the air flow from the primaries to be diverted to the booster when high compression of the air is needed. When higher compression is not needed the booster compressor is isolated with the check valves in the flow...

Sample Catcher

Imt Rock Drill Bit

Sample catchers are usually required for any air and gas drilling operation. The sample catcher allows small rock cutting samples to be obtained from a well during the drilling operation. The sample catcher is installed in the body of the blooey line usually near the entrance to the blooey line see Figure 2-14 . Figure 2-16 shows a typical sample catcher design. This design has a small diameter 2 inch nominal diameter or smaller transport pipe welded through the blooey line body. A short...

Primary and Secondary Jets

Flow Line Pit

Figure 2-14 shows the exit positions in the blooey line of the primary and secondary jet flow lines from the compressors. Figure 2-15 shows the high pressure vent lines from the compressor for the primary and secondary jet flow lines. These jet flow line installations in the blooey line are only required for drilling operations directed toward the recovery of oil, natural gas, or geothermal gas products. Primary and secondary jets are incorporated into the blooey line to allow the safe venting...

Drag Bits

Drag bits have fixed cutter blades or elements that are integral with the body of the bit. The earliest drag bits were simply steel cutter blades rigidly attached to a steel body that is made up to the bottom of the drill string. Later natural diamonds were used as the cutter elements. A diamond drill bit has natural diamonds that are embedded in a tungsten carbide matrix body that is made up to the bottom of the drill string. The most recent development in drag bit technology is the...

Downhole Equipment

Air and gas drilling operations require some special subsurface equipment and drilling methods that are not normally used in rotary mud drilling operations. Deep direct circulation operations use rotary drill strings that are similar to those used in mud drilling. But even these drill strings are equipped with downhole tools unique to air and gas drilling operations. Larger diameter shallow and intermediate depth wells are usually drilled with reverse circulation techniques. These techniques...

Preface

This is the second edition of the Air and Gas Drilling Manual. The first edition of this book was published in 1984 by Gulf Publishing company of Houston, Texas. The first edition of the book was written primarily for the oil and gas recovery drilling industry. This first edition had moderate success and was sold out of the initial printing by the late 1980's. However, in the early 1990's underbalanced drilling became an important technology for oil and gas recovery drilling and completions....

Scrubber

The scrubber removes excess water in the compressed air flow in the flow line. If the humidity of the atmospheric air is high, then as the air is compressed in the compressors much of the water will return to the liquid state. Dry air drilling operations require the removal of this water before the compressed air is injected into the well. The scubber is incorporated into a surge tank. The water in the compressed air flow is collected in the bottom of the surge tank as the air flows through...

Burn Pit Oil And

Figures 2-1 and 2-14 show the burn pit at the exit end of the blooey line. The burn pit should always be located away from the standard mud drilling reserve pit water storage for an emergency mud drilling operation . This design of pit location prevents any hydrocarbon liquids from flowing into the reserve pit, thus, preventing reserve pit fires near the rig. The burn pit is located downwind from the drilling rig. Such a location keeps the smoke and any dust from the drilling operation from...

Gas Detector

Gas detectors gas sniffers are used only in air drilling operations directed at the recovery of oil and natural gas. Figure 2-14 shows the position of the gas detector on the blooey line. This detector can detect very small quantities of hydrocarbons that might enter the blooey line from the annulus. As the drill bit is advanced and hydrocarbon producing formations are drilled, the hydrocarbons are entrained in the return air flow to the surface with entrained rock cuttings. The detector alerts...

DeDuster

Dusters Design

De-dusters are usually required for any air or gas drilling operation. Figure 2-14 shows the location of the de-duster near the exit end of the blooey line. Figure 2-17 shows a typical de-duster design. The de-duster is a small diameter pipe 2 inch nominal diameter or smaller water system located inside the blooey line. A pump supplies the system with water. The water is sprayed on the dry rock dust particles that exit the line. This reduces or eliminates the dust clouds that are typical of dry...

Centrifugal Compressors

Centrifugal Compressor

The centrifugal compressor was the earliest developed dynamic compressor. This type of compressor allows for the continuous flow of the gas through the machine. There is no distinct closed boundary enclosure in which compression takes place. The compression of the gas results from the speed of the flow through a specified geometry within the compressor. The basic concept of the centrifugal compressor is the use of centrifugal forces on the gas created by high velocity flow of the gas in the...

Kelly Sub Valves

Float Valve Sub

At the top of the drill string just above the kelly is a kelly cock sub which is fitted with a ball valve see Figure 3-1 . In the event of a subsurface blowout, the kelly cock's ball valve can be closed and the sub left made up to the top of the kelly. With the ball valve closed, a pressure gauge can be made up to the top of the sub. Using this pressure gauge, the ball valve can be opened and vital pressure information obtained for the pressure inside the drill string together with casing head...

References

J., Personal communication, November 1982. 2. Moore, W. W., Fundamentals of Rotary Drilling, Energy Publications, 1981. 3. Hook, R. A., Cooper, L. W., and Payne, B. R., Air, Mist and Foam Drilling A Look at Latest Techniques Parts I and II, World Oil, April and May 1977. 4. Bulletin on Performance Properties of Casing, Tubing, and Drill Pipe, API Bul 5C2, Twentieth Edition, May 31, 1987. 5. API Specification for Line Pipe, API Spec 5L, Thirty-Fourth Edition, May 31, 1984. 6. API...

Standard Units

In the United States a unit of air or any gas is referenced to the standard cubic foot of dry air. The API Mechanical Equipment Standards standard atmospheric conditions for dry air is a temperature of 60 F which is 459.67 60 519.67 R and a pressure of 14.696 psia 760 mm, or 29.92 inches Hg . The equation of state for the perfect gas can be written as where - is the pressure lb ft2 abs , Ru is the universal gas constant which is 1,545.4 ft-lb lb-mole- R , T is the temperature R , mw is the mole...

Compressor Classification

Compressor Types Compressor Types

Similar to the classification of pumps, compressors are grouped in one of two general classes continuous flow i.e., dynamic compressors, and intermittent flow i.e., positive displacement compressors see Figure 4-1 1, 2 . Intermittent flow or positive displacement compressors move the compressible fluid through the compressor in separate volume packages of compressed fluid these volume packages are separated by moving internal structures in the machine . The most important subclass examples of...

Pilot Light

Figures 2-1 and 2-14 show a pilot light at the end of the blooey line. Pilot lights are used only in air or gas drilling operations directed at the recovery of oil and natural gas. The pilot light is a small open flame propane or natural gas maintained at the end of the blooey line to ignite and burn any hydrocarbons that might exit the line as the drilling operation progresses. Many new air and gas drilling operations are equipped with electric igniters instead of open flame pilot lights.

Drilling Location

High Pressure Mud Lines

Nearly all air and gas drilling operations are land operations. Figure 2-1 shows a typical air drilling location plan for the drilling rig and the other important surface equipment 1 . The plan in this figure shows the location of the drilling rig borehole directly below the rotary table . This is a typical triple drilling rig configuration. The drilling rig floor is larger and, therefore, it is easier to show the important features of an air drilling operation with this type of rig. This rig...

Gauges

Each of the compressors is equipped with independent gauges to assess its operating performance. In addition to the compressor gauges are those placed along the flow line. A low pressure gauge is placed downstream of the primary compressors but upstream of the booster compressor. This gauge allows assessment of the performance of the primaries. A high pressure gauge is placed downstream of the booster compressor to assess the performance of the primaries and booster when high pressure...

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Iadc Drilling String

Figure 3-21 Heavy-weight drill pipe standing in rig rack courtesy of Smith International . The unique characteristic of this type of drill pipe is that it can be run in compression in the same manner as drill collars. Most heavy-weight drill pipe is fabricated in Range 2 and 3 API lengths. It is also available in custom lengths shorter than Range 2. Heavy-weight drill pipe are available in 3 1 2 inch, 4 inch, 4 1 2 inch, and 5 inch, 5 1 2 inch, and 6 5 8 inch nominal outside diameters. Figure...

Introduction

This engineering practice book has been prepared for engineers, earth scientists, and technicians who work in modern rotary drilling operations. The book derives and illustrates engineering calculation techniques associated with air and gas drilling technology. Since this book has been written for a variety of professionals and potential applications, the authors have attempted to minimize the use of field equations. Also the technical terminology used in the book should be easily understood by...

Air Drilling Flowline

Air and gas drilling operations require a variety of flow line designs from the drilling rig. Drilling operations using compressed air or other compressed gases require the use of large inside diameter flow lines. These return flow lines should be designed not to choke the air or gas flow as it exits the circulating system. This line is known as the blooey line which derives its name from the sound made when a slug of formation water is ejected from the line with high velocity air or gas see...

Float Valves

Figure 3-29 shows a typical drill string float valve. This is a safety valve device and is usually placed in the bit sub at the bottom of the drill string. These valves are used in nearly all deep rotary air and gas drilling operations. The valve prevents the back flow of compressed air or other gas and entrained rock cuttings from entering the annulus space into the inside of the drill string. The valve is fitted with a flapper mechanism. If circulation is stopped the compressed air and rock...

Volumetric Flow Rate Meters

Orifice Gas Flow Meter

No driller would carry out a mud drilling operation without knowing the volumetric flow rate of mud being circulated to the well. The volumetric flow rate from a mud pump can be easily assessed by either counting strokes per minute of the mud pump and knowing the capacity of the pump in gallons per stroke and then calculating the output of the pump in gallons per minute , or by providing the rig floor with an accurate volumetric flow rate gauge. The volumetric flow rate of air or other gases to...

Drill String Design

One of the initial planning steps for a rotary drilling operation is the design of the drill string. The drill string must have the strength to drill to the intended target depth and be light enough so that the hoisting system can extract the string from the well when the target depth has been reached. Described below is the API procedure for drill string design 1 . The axial tension force or load , F lb , at the top of the drill string in a vertical well is where Lp is the length of the drill...

Rotary Drilling

Crowsnest Drilling Rig

Rotary drilling is a method used to drill deep boreholes in rock formations of the earth's crust. This method is comparatively new, having been first developed by a French civil engineer, Rudolf Leschot, in 1863 3 . The method was initially used to drill water wells using fresh water as the circulation fluid. Today this method is the only rock drilling technique used to drill deep boreholes greater than 3,000 ft . It is not known when air compressors were first used for the drilling of water...

Dual Wall Pipe

Drill Pipe Connection Table

Dual wall drill pipe elements are used exclusively in reverse circulation drilling operations. This type of drill pipe is used for drilling shallow 3,000 ft or less water wells, environmental monitoring wells, geotechnical boreholes, and mining boreholes. These rotary drilling operations can be a rotation of the dual wall pipe drill string with a tri-cone or drag type bit, b rotation of the dual wall pipe drill string with a standard downhole air hammer with standard air hammer bit , or c...

Blooey Line

Figure 2-1 shows the blooey line exiting from the drilling rig annulus for direct circulation operations. Blooey lines or equivalent are required for all air and gas drilling operations and are needed to keep drilling rock dust and cuttings away from the drilling rig and rig personnel. Blooey lines must be secured to the ground surface with tie-downs see Figure 2-1 . The high velocity of the air or gas flow from the well will interact with the flexible blooey line to set up an aerodynamic...

Water Injection Pump

Foam Air Drilling

Unstable foam mist drilling operations require the injection of water into the compressed air flow before the air is injected into the well. The water injection pump injects water, chemical corrosion inhibitors, and liquid foamers into the compressed air flow line. Figure 2-2 shows a skid mounted water injection pump for air and gas drilling operations. These skid mounted water injection pumps are used for the deep drilling operations. These pumps are capable of injecting up to 20 bbl hr at 42...

Bottomhole Assembly

Bottom Hole Assembly Vertical

Figure 3-16 shows a typical bottomhole assembly BHA for a direct circulation rotary drilling operation. The BHA is the section of the drill string below the drill pipe see Figure 3-1 . This section of the drill string is the most rigid length of the string. It is this section of the drill string that determines how much weight can be placed on the drill bit and how straight a vertical borehole will be drilled with the drill string. Figure 3-16 Typical bottomhole assembly for direct circulation...

Direct Circulation

Oil Rig Bottom Into Ground

Figure 1-6 shows a schematic of a rotary drilling, direct circulation mud system that would be used on a typical double and triple drilling rig. Direct circulation requires that the drilling mud or treated water flow from the slush pump or mud pump , through the standpipe on the mast, through the rotary hose, through the swivel and down the inside of the kelly, down the inside of the drill pipe and drill collars, through the drill bit at the bottom of the borehole into the annulus space between...

I

Figure 3-3 Dual wall pipe drill string Foremost Industries Incorporated . for reverse circulation operations courtesy of The drill string for a dual wall pipe reverse circulation air drilling operations is rather simple. These specially fabricated reverse circulation drill bits have a threaded box connection. The bit sub has a threaded pin connection down and threaded box connection up. The bottom threaded pin connection of the bottom dual wall pipe joint in the drill string is made up to the...

Air Hammer Bits

Rock Formation Abrasiveness

Percussion air hammers have been used for decades in shallow air drilling operations. These shallow operations have been directed at the drilling of water wells, monitoring wells, geotechnical boreholes, and mining boreholes. In the past decade, however, the percussion air hammers have seen increasing use in drilling deep oil and natural gas wells. Percussion air hammers have a distinct advantage over roller cutter bits in drilling abrasive, hard rock formations. The use of percussion air...

Stabilizers and Reamers

Oilwell Bha

Stabilizers and rolling cutter reamers are special thick walled drill collar subs that are placed in the BHA to force the drill collars to rotate at or near the center of the borehole. By keeping the drill collars at or near the center of the borehole the drill bit will drill on a nearly straight course projected by the center axis of the rigid BHA. Stabilizers and rolling cutter reamers have blades or rolling cutters that protrude from the sub wall into the annulus to near the borehole...

Wellhead Equipment

All air and gas drilling operations require the use of a rotating head or similar air or gas flow diverter which is installed below the rotary table. The blowout preventer BOP stack is always used when subsurface overpressured dangerous gases or fluids might be encountered while drilling i.e., oil and natural gas drilling operations, and geothermal drilling operations . Figure 2-7 shows schematics of three typical wellhead assemblies for double and triple drilling rigs set up for air and gas...

Rotating Head

Rotating Bop

The rotating head or a similar air flow diverter was developed for use in air and gas drilling operations to keep air or gas with entrained rock cuttings from flowing to the drilling rig floor through the rotary table kelly bushings. Diverting this drilling fluid flow from the drilling rig floor is mandatory for all air and gas drilling operations. Even on small drilling rigs the air exiting the annulus direct circulation must be diverted in order to provide a safe work space for the rig...

Standard Drill String

Drill Pipe Tool Joint Diagram

Figure 3-1 shows a schematic of a standard rotary drill string used to drill deep boreholes with direct circulation. Such a drill string would be used on large drilling rigs. At the bottom of the drill string is the drill bit. The drill bit is threaded made-up to a bit sub. The drill bit has a male thread or threaded pin pointing up. The bit sub is a short thick wall pipe that has a female thread or threaded box on both ends. Above the bit sub are the drill collars. Each of the drill collars...

Drill Collars

Drill collars are thick walled tubulars that are used at the bottom of the drill string see Figure 3-1 . Their principal purpose in the drill string is to provide the axial force needed to advance the drill bit see Figure 1-2 . When drilling a vertical borehole, the axial force is the weight of the drill collars. Drill collars are available in API range lengths given in Table 1-1. Figure 3-16 shows a BHA with Range 2 30 ft long drill collars. Range 2 lengths are typical for double and triple...

Blowout Prevention Stack

Blowout Prevention

Blowout prevention equipment was developed for use in drilling deep wells for the recovery of oil and natural gas. Later this unique oil and gas industry equipment was adapted for use in drilling deep geothermal wells. Natural deposits of oil and gas exist in porous rock formations deep in the earth's crust. These deposits were created by millions of years of sediment burial and confinement by geologic structures. Over time, increased sedimentary burial created high pressures and temperatures...

Reverse Circulation

Udr Drill Rig Top Head Drive

Rotary drilling reverse circulation either using drilling mud and or compressed air or gas can be a useful alternative to direct circulation methods. The reverse circulation technique is particularly useful for drilling relatively shallow large diameter boreholes. In a typical reverse circulation operation utilizing drilling mud, the drilling mud or treated water flows from the slush pump or mud pump to the top of the annulus between the outside of the drill string and the inside the borehole,...

Downhole Surveying Equipment

BHAs for drill strings used to drill deep vertical wells are usually fitted with several nonmagnetic drill collars. These drill collars are usually near the bottom of the BHA just above the drill bit . These non-magnetic collars are needed to carry out the downhole surveys required by most natural resource regulatory agencies. Downhole surveys are used to describe the deviation of a drilled borehole from the ideal vertical centerline of the intended well. Knowledge of where an actual well has...

Flow Characteristics

Drill String Design Calculations

A comparison is made of the flow characteristics of mud drilling and air drilling in an example deep well. A schematic of this example well is shown in Figure 115. The well is cased from the surface to 7,000 ft with API 8 5 8 inch diameter, 28.00 lb ft nominal, casing. The well has been drilled out of the casing shoe with a 7 7 8 inch diameter drill bit. The comparison is made for drilling at 10,000 ft. The drill string in the example well is made up of bottom to top , 7 7 8 inch diameter drill...

Classification of Drill Bits

The International Association of Drilling Contractors IADC has approved a standard classification system for identifying similar bit types available from various manufacturers 5 . Table 3-1 gives an example IADC classification chart for insert drill bits first column . In general, the classification system adopted is a three-digit code. The first digit in the bit classification code is the rock formation series number. The letter D precedes the first digit if the bit is diamond or PDC drag type...

Roller Cutter Bits

Single Roller Bits

Roller cutter bits use a crushing action to remove rock from the cutting face and advance the drill bit. The weight or axial force that is applied to the drill bit is transferred to the tooth or teeth on the bit. These teeth are pointed mill tooth bit or rounded insert tooth bit and the force applied is sufficient to fail the rock in shear and tension and cause particles of the rock to separate from the cutting face. The drill bits are designed to remove a layer of rock with each successive...

Drill Rod Material Properties

Boart Longyear Diameter

Small rotary drilling rigs often use drill rod as a drill pipe substitute. Drill rod is used in mining, environmental, and geotechnical drilling operations. These rods are available in 2 ft, 5 ft, and 10 ft lengths. They are used in both mud or water and air drilling operations. There are two types of drill rods, wireline drill rods, and conventional drill rods. Figure 3-23 shows a schematic profile of wireline drill rod. This type of drill rod has no change in inside diameter at the...

Dual Wall Pipe Drill String

Intermediate and shallow depth large diameter wells can be drilled with direct circulation techniques. But reverse circulation techniques are more efficient and are the preferred techniques. The drilling industry has developed some very unique downhole tools for reverse circulation air drilling operations. Figure 3-3 shows a schematic configuration of a rotary reverse circulation operation using dual wall drill pipe. Reverse circulation techniques are not restricted to air drilling operations....