裝配圖沖擊回轉(zhuǎn)鉆進(jìn)技術(shù)
裝配圖沖擊回轉(zhuǎn)鉆進(jìn)技術(shù),裝配,沖擊,回轉(zhuǎn),鉆進(jìn),技術(shù)
本科生畢業(yè)設(shè)計（論文）
翻譯資料
中文題目： 空氣及天然氣鉆井
英文題目： Air and Gas Drilling
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論文翻譯
Chapter One 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 all those who study this technology. In nearly all parts of the book,equations are presented that can be used with any set of consistent units. Although most of the example calculations use English units, a reader can easily convert to the Systeme Internationale d’Units (SI units) using the tables in Appendix A.
Air and gas drilling technology is the utilization of compressed air or other gases as a rotary drilling circulating fluid to carry the rock cuttings to the surface that are generated at the bottom of the well by the advance of the drill bit. The compressed air or other gas (e.g., nitrogen or natural gas) can be used by itself, or can be injected into the well with incompressible fluids such as fresh water,
formation water, or formation oil. There are three distinct operational applications for this technology: air or gas drilling operations (using only the compressed air or other gas as the circulating fluid), aerated drilling operations (using compressed air or other gas mixed with an incompressible fluid), and stable foam drilling operations (using the compressed air or other gas with an incompressible fluid to create a continuous foam circulating fluid).
1.1 Rotary Drilling
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 wells,but it is known that deep petroleum and natural gas wells were drilled utilizing portable air compressors in the 1920’s [4]. Pipeline gas was used to drill a natural gas well in Texas in 1935 using reverse circulation techniques [5].
Today rotary drilling is used to drill a variety of boreholes. Most water wells and environmental monitoring wells drilled into bedrock are constructed using rotary drilling. In the mining industry rotary drilling is used to drill ore body test boreholes and pilot boreholes for guiding larger shaft borings. Rotary drilling techniques are used to drill boreholes for water, oil, gas, and other fluid pipelines that need to pass under rivers, highways, and other natural and man-made obstructions. Most recently, rotary drilling is being used to drill boreholes for fiber optics and other telecommunication lines in obstacle ridden areas such as cites and industrial sites. The most sophisticated application for rotary drilling is the drilling of deep boreholes for the recovery of natural resources such as crude oil, natural gas, and geothermal steam and water. Drilling boreholes for fluid resource recovery requires boreholes drilled to depths of 3,000 ft to as much as 20,000 ft.
Rotary drilling is highly versatile. The rotary drilling applications given aboverequire the drilling of igneous, metamorphic, and sedimentary rock. However, the deep drilling of boreholes for the recovery of crude oil and natural gas are almost exclusively carried out in sedimentary rock. Boreholes for the recovery of geothermal steam and water are constructed in all three rock types. The rotary drilling method requires the use of a rock cutting or crushing drill bit. Figure 1-1 shows a typical mill tooth tri-cone roller cone bit. This type of drill bit uses more of a crushing action to advance the bit in the rock (see Chapter 3 for more details).This type of bit is used primarily in the drilling of sedimentary rock.
To advance the drill bit in rock requires the application of an axial force on the bit (to push the bit into the rock face), torque on the bit (to rotate the bit against the resistance of the rock face), and circulating fluid to clear the rock cuttings away from the bit as the bit generates more cuttings with its advance (see Figure 1-2).
Rotary drilling is carried out with a variety of drilling rigs. These can be small“single” rigs, or larger “double” and “triple” rigs. Today most of the land rotary drilling rigs are mobile units with folding masts. A single drilling rig has a vertical space in its mast for only one joint of drill pipe. A double drilling rig has a vertical space in its mast for two joints of drill pipe and a triple drilling rig space for three joints. Table 1-1 gives the API length ranges for drill collars and drill pipe [6].
Figure 1-3 shows a typical single drilling rig. Such small drilling rigs are highly mobile and are used principally to drill shallow (less than 3,000 ft in depth) water wells, environmental monitoring wells, mining related boreholes, and other geotechnical boreholes. These single rigs are usually self-propelled. The selfpropelled drilling rig in Figure 1-3 is a George E. Failing Company Star 30K.
These rigs typically use Range 1 drill collars and drill pipe.
Single rigs can be fitted with either an on-board air compressor, or an on-board mud pump. Some of these rigs can accommodate both subsystems. These rigs have either a dedicated prime mover on the rig deck, or have a power-take-off system which allows utilization of the truck motor as a prime mover for the drilling rig equipment (when the truck is stationary). These small drilling rigs provide axial force to the drill bit through the drill string via a chain or cable actuated pull-down system, or hydraulic pull-down system. A pull-down system transfers a portion of the weight of the rig to the top of the drill string and then to the drill bit. The torque and rotation at the top of the drill string is provided by a hydraulic tophead drive (similar to power swivel systems used on larger drilling rigs) which is moved up and down the mast (on a track) by the chain drive pull-down system. Many of
these small single drilling rigs are capable of drilling with their masts at a 45? angle to the vertical. The prime mover for these rigs is usually diesel fueled.
Figure 1-4 shows a typical double drilling rig. Such drilling rigs are also mobile and can be self-propelled or trailer mounted. Figure 1-5 shows the schematic of a self-propelled double drilling rig.
The trailer mounted drilling rig in Figure 1-4 is a George E. Failing Company SS-40. These double rigs have the capability to drill to depths of approximately 10,000 ft and are used for oil and gas drilling operations, geothermal drilling operations, deep mining and geotechnical drilling operations, and water wells. Double rigs typically use Range 2 drill collars or drill pipe. These rigs are fitted with an on-board prime mover which operates the rotary table, drawworks, and mud pump. The axial force on the drill bit is provided by drill collars. The torque and rotation at the top of the drill string is provided by the kelly and the rotary table.The double drilling rigs have a “crows nest” or “derrick board” nearly midway up the mast. This allows these rigs to pull stands of two drill collar joints or two drill pipe joints. These rigs can carry out drilling operations using drilling mud (with the
on-board mud pump) or using compressed air or gas drilling fluids (with external compressors). A few of these drilling rigs are capable of drilling with their masts at a 45? angle to the vertical. The prime mover for these rigs is usually diesel fueled,but can easily be converted to propane or natural gas fuels.
Triple drilling rigs are available in a variety of configurations. Nearly all of these drilling rigs are assembled and erected from premanufactured sections. The vertical tower structure on these drilling rigs are called derricks. The smaller triple land rigs can drill to approximately 20,000 ft and utilize Range 2 drill collars and drill pipe. Very large triple drilling rigs are used on offshore platforms. These rigs can utilize Range 3 drill collars and drill pipe.
The schematic layout in Figure 1-5 shows a typical self-propelled double drilling rig. This example rig is fitted with a mud pump for circulating drilling mud. There is a vehicle engine that is used to propel the rig over the road. The same engine is used in a power-take-off mode to provide power to the rotary table,drawworks, and mud pump. For this rig, this power-take-off engine operates a hydraulic pump which provides fluid to hydraulic motors to operate the rotary table,
drawworks, and mud pump. The “crows nest” on the mast indicates that the rig is capable of drilling with a stand of two joints of drill pipe. This drilling rig utilizes a rotary table and a kelly to provide torque to the top of the drill string. The axial force on the bit is provided by the weight of the drill collars at the bottom of the drill string (there is no chain pull-down capability for this drilling rig). This
example schematic shows a rig with on-board equipment that can provide only drilling mud or treated water as a circulate fluid. The small air compressor at the front of the rig deck is to operate the pneumatic controls of the rig. However, this rig can easily be fitted for air and gas drilling operations. This type of drilling rig(already fitted with a mud pump), would require an auxiliary hook up to external air compressor(s) to carry out an air drilling operation. Such compressor systems and
associated equipment for air drilling operations are usually provided by asubcontractor specializing in these operations.
1.2 Circulation Systems
Two types of circulation techniques can be used for either a mud drilling system or an air or gas drilling system. These are direct circulation and reverse circulation.
1.2.1 Direct Circulation
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 the outside of the drill string and the inside of the borehole. The drilling mud entrains the rock bit cuttings and then flows with the cuttings up the annulus to the surface where the cuttings are removed from the drilling mud by the shale shaker;the drilling mud is returned to the mud tanks (where the slush pump suction side picks up the drilling mud and recirculates the mud back into the well). The slush pumps used on double (and triple) drilling rigs are positive displacement piston type
pumps.
For single drilling rigs, the drilling fluid is often treated fresh water in a pit dug in the ground surface and lined with an impermeable plastic liner. A heavy duty hose is run from the suction side of the on-board mud pump (see Figure 1-5) to the mud pit. The drilling water is pumped from the pit, through the pump, through an on-board pipe system, through the rotary hose, through the hydraulic tophead drive, down the inside of the drill pipe, and through the drill bit to the bottom of the well.
The drilling water entrains the rock cuttings from the advance of the bit and carries the cuttings to the surface via the annulus between the outside of the drill pipe and the inside of the borehole. At the surface the drilling fluid (water) from the annulus with entrained cuttings is returned to the pit where the rock cuttings are allowed to settle out to the bottom. The pumps on single drilling rigs are small positive displacement reciprocating piston or centrifugal type.
Figure 1-7 shows a detailed schematic of a direct circulation compressed air drilling system that would be used on a typical double or triple drilling rig. Direct circulation requires that atmospheric air be compressed by the compressor and then forced 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 the outside of the drill string and the inside of the borehole. The compressed air entrains the rock bit cuttings and then flows with the cuttings up the annulus to the surface where the compressed air with the entrained cuttings exit the circulation system via the blooey line. The compressed air and cuttings exit the blooey line into a large pit dug into the ground surface (burn pit). These pits are
lined with an impermeable plastic liner.
In order to safely drill boreholes to these deposits heavily weighted drilling muds are utilized. The heavy fluid column in the annulus provides the high bottomhole pressure needed to balance (or overbalance) the high pore pressure of the deposit.
Figure 1-13 also shows that the heavier the drilling fluid column in the annulus the more useful the drilling fluid is for controlling high pore pressure (the arrow points downward to increasing capability to control high pore pressure). There are limits to how heavy a drilling mud can be. As was discussed above, too heavy a drilling mud results in overbalanced drilling and this can result in formation damage. But there is a greater risk to overbalanced drilling. If the drilling mud is too heavy the rock formations in the openhole section can fracture. These fracturescould result in a loss of the circulating mud which could result in a blowout.
In the past decade it has been observed that drilling with a circulation fluid that has a bottomhole pressure slightly below that of the pore pressure of the fluid deposit gives near optimum results. This type of drilling is denoted as underbalanced drilling. Underbalanced drilling allows the formation to produce fluid as the drilling progresses. This lowers or eliminates the risk of formation damage and eliminates the possibility of formation fracture and loss of circulation. In general, if the pore pressure of a deposit is high, an engineered adjustment to the drilling mud weight (with additives) can yield the appropriate drilling fluid to assure underbalanced drilling. However, if the pore pressure is not unusually high then air and gas drilling techniques are required to lighten the drilling fluid column in the annulus.
Figure 1-14 shows a schematic of the various drilling fluids and their respective potential for keeping formation water out of the drilled borehole. Formation water is often encountered when drilling to a subsurface target depth. This water can be in fracture and pore structures of the rock formations above the target depth. If drilling mud is used as the circulating fluid, the pressure of the mud column in the annulus is usually sufficient to keep formation water from flowing out of the exposed rock formations in the borehole. The lighter drilling fluids have lower bottomhole pressure, thus, the lower the pressure on any water in the exposed fracture or pore structures in the drilled rock formations. Figure 1-14 shows that the heavier drilling fluids have a greater ability to cope with formation water flow into to the borehole(the arrow points downward to increasing control of formation water).
1.3.2 Flow Characteristics
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 1-15. 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 bit, ~ 500 ft of 6 3/4 inch outside diameter by 2 13/16 inch inside diameter drill collars, and ~ 9,500 ft of API 4 1/2 inch diameter, 16.60 lb/ft nominal, EUS135,NC 50, drill pipe.
The mud drilling hydraulics calculations are carried out assuming the drilling mud weight is 10 lb/gal (75 lb/ft3), the Bingham mud yield is 10 lb/100 ft2, and the plastic viscosity is 30 centipose. The drill bit is assumed to have three 13/32 inch diameter nozzles and the drilling mud circulation flow rate is 300 gals/minute. Figure 1-16 shows the plots of the pressures in the incompressible drilling mud as a function of depth. In the figure is a plot of the pressure inside the drill string. The pressure is approximately 1,400 psig at injection and 6,000 psig at the bottom of the inside of the drill string just above the bit nozzles. Also in the figure is a plot of the pressure in the annulus. The pressure is approximately 5,440 psig at the bottom of the annulus just below the bit nozzles and 0 psig at the top of the annulus at the surface.
The pressures in Figure 1-16 reflects the hydrostatic weight of the column of drilling mud and the resistance to fluid flow from the inside surfaces of the drill string and the surfaces of the annulus. This resistance to flow results in pressure losses due to friction. The total losses due to friction are the sum of pipe wall, openhole wall, and drill bit orifice resistance to flow. This mud drilling example
shows a drilling string design which has a open orifice or large diameter nozzle openings in the drill bit. This is reflected by the approximate 700 psi loss through the drill bit. Smaller diameter nozzles would yield higher pressure losses across the drill bit and higher injection pressures at the surface.
The air drilling calculations are carried out assuming the drilling operation is at sea level. There are two compressors capable of 1,200 scfm each, so the total volumetric flow rate to the drill string is 2,400 scfm. The drill bit is assumed tohave three open orifices (~0.80 inches diameter). Figure 1-17 shows the plots of the pressures in the compressible air as a function of depth. In the figure is a plot of the pressure inside the drill string. The pressure is approximately 260 psia at injection and 270 psia at the bottom of the inside of the drill string just above the bit orifices. Also in the figure is a plot of the pressure in the annulus. The pressure is approximately 260 psia at the bottom of the annulus just below the bit orifices and 14.7 psia at the end of the blooey line at the surface (top of the annulus).
As in the mud drilling example, the pressures in Figure 1-17 reflects the hydrostatic weight of the column of compressed air and the resistance to air flow from the inside surfaces of the drill string and the surfaces of the annulus. This resistance to flow results in pressure losses due to friction. In this example the fluid is compressible. Considering the flow inside the drill string, the hydrostatic weight of the column dominates the flow (relative to friction losses) and this results in the
injection pressure at the surface being less than the pressure at the bottom of the drill
string (inside the drill string above the bit open orifices).
Figure 1-18 shows the plots of the temperature in the incompressible drilling mud as a function of depth. The geothermal gradient for this example is 0.01?F/ft. Subsurface eart
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