MXPA97004505A - Method and apparatus for perforating with reduced content liquid of soli - Google Patents

Abstract

The present invention relates to a method for drilling a hole comprising the steps of: driving a drilling assembly that terminates in a drill bit within a hole, pumping a drilling fluid of reduced solids content through the assembly of perforation and out of the drill bit, where the drilling fluid strikes and disintegrates forming material in cooperation with the drill, continuously pumping an annular fluid having a greater density than that of the drilling fluid into a ring between the hole and the drill. drilling assembly, while drilling the forming material, wherein the annular fluid substantially extends from the surface of the bit, and returning the drilling fluid and cuts resulting from the disintegration of the forming material to the surface through of a substantially unobstructed tubular passage in the drilling assembly, said method being characterized by which allows to control a selected pressure of the annular fluid in the ring so that an interface is formed in the drill bit, allowing the interface that the annular fluid mix with the drilling fluid and return together with the drilling fluid and the cuts to the surface, but substantially preventing the drilling fluid from entering the anil

Description

ETQDO AND APPARATUS FOR PERFORATING WITH HIGH PRESSURE LIQUID OF REDUCED SOLID CONTENT TECHNICAL FIELD The present invention relates generally to methods and apparatus for drilling land formations. More particularly, the present invention relates to methods and apparatus for drilling terrestrial formations for oil recovery using a high pressure, low solids content liquid.

BACKGROUND OF THE INVENTION It is a long-standing practice in rotary well drilling to use a drilling fluid. In most cases, the drilling fluid is a dense slurry, forming a filter layer to protect and retain the wall of the drilling hole. The mud is pumped by the tubular drill string, exits the nozzles in the drill bit and is returned to the surface in the ring between the drill string and the side wall of the drill hole. This fluid cools and lubricates the drill bit and at the same time provides a hydrostatic column of fluid to avoid kicks or explosions of gas and develops the filter layer in formation in the side wall of the drilling hole. The drilling fluid exits the bit through the nozzles to strike the bottom of the well with sufficient velocity p > To quickly remove by torrent the cuts created by the teeth of the drill. It is known that the higher the fluid velocity, the faster the drilling speed, especially in the softer formations that can be removed with a high velocity fluid. Although it is well known that mud hydraulics using high nozzle velocities beneficially affect the penetration speed of the bit, the drilling fluid is generally not employed as the main mechanism for the disintegration of the forming material. One reason for this is that conventional drilling muds are considerably abrasive, although there is an effort to reduce the amount of abrasives. The pressures required to generate enough hydraulic horsepower to actively disintegrate the forming material cause extreme abrasive wear on the drill bit, especially the nozzles, and the components associated with the drill string when there are abrasive particles in the fluid of the drill. drilling. The use of pure water or a non-abrasive fluid would solve the problem of abrasion, but the density and characteristics of such fluids can not replace the dense, drilling mud that forms the filter layer in the formations that are porous and tend to break off. Nor can pure water be used when a high-pressure gas may be encountered and a high-density fluid is required to avoid an explosion. Attempts have been made to employ a high pressure, low solids content drilling fluid together with a dense drilling mud, which forms a filter layer to achieve the advantages of both. The Patent of E.U.fl. No. 2,951,580, dated September 6, 1980, assigned to Carnp, describes a two-fluid drilling system in which an inflatable packer is rotatably coupled to the drill string just above the drill bit. In the drilling operation, the packer is inflated and the ring is filled between the drill string and the wall of the drilling hole above the packer with conventional drilling mud. As the gaseous or reduced density drilling fluid goes down through the drill string and out of a drill bit. The packer avoids the mixing of the drilling fluids and the ring. The drilling fluid loaded with cuts is returned to the surface through a hole in the side wall of the drill string below the packer and a duct formed inside the drill string. The presence of a packer near the drill bit in the drill rope raises design and reliability issues. Additionally, the perforation fluid loaded with cuts is returned through a tortuous passage in the drill string, which is likely to get stuck with cuts. The Patent of E.U.A. No. 3,268.01 ?, of August 23, 1966, assigned to Yarbrough describes a method and apparatus for drilling with two fluids in which a concentric two-pipe drill string is employed. Pure water or drilling fluid is used and pumped down through the inner tube of the drill string and out of the bit. A slurry or drilling fluid is maintained that covers the wall in the ring between the drill string and the drill hole. The piercing fluid loaded with cuts is returned to the surface through the ring defined between the inner and outer concentric tubes of the drill string. The height of the column of the drilling mud covering the wall is monitored and the pressure in the drilling fluid is increased, sensitive to the pressure increases that result from the changes in the hydrostatic pressure associated with the column of the liquid covering the wall between the drill string and the wall of the drill hole. Returning the cut edge loaded in a ring between the inner and outer conduits on a drill string would be problematic because the ring would tend to get stuck and would be difficult to clean. Additionally, monitoring the pressure exerted by the ring fluid by measuring the height at the well bore would be extremely difficult to perform if the ring fluid or drilling mud is continuously pumped into the ring, which is necessary to maintain the fluid of the ring or the drilling mud especially to the length of the drilling hole as the drilling progresses. The patent of E.U.A. No. 4,718,503, dated January 12, 19T8 assigned to Stewart discloses a method for drilling a drill hole in which a drill bit is coupled to the lower end of a pair of concentric drill pipes. A first low viscosity fluid, such as oil and water, is pumped down through the inner bore tube and returned to the surface through the ring between the inner and outer bore tubes. A column of the annular fluid or the drilling mud is held stationary in the ring formed between the wall of the drilling hole and the outside of the drill pipes. When it becomes necessary to form a new perforation tube section, the filter layer forming drilling mud is pumped down to the lower perforation tube to displace the transparent drilling fluid, wherein only a dense, layer forming fluid is formed. of filter occupies the drilling hole. Such a procedure for the formation of new sections of the drill pipe is extremely difficult to handle and in practice is uneconomical. There is a need, therefore, for a method and apparatus for drilling with a reduced density drilling fluid while maintaining a dense, ring-forming filter fluid in the ring that is commercially practical.

BRIEF DESCRIPTION OF THE INVENTION It is a general object of the present invention to provide an improved method and apparatus for drilling a hole using a high pressure drilling fluid of reduced solids content, while maintaining an annular fluid having a density higher than that of the fluid of drilling in the ring between the drill hole and the drill string while drilling. This and other objects of the present invention are fulfilled by moving a drill string that ends in a drill bit to a drill hole. A drilling fluid of reduced solids content is pumped through the drill string and out of the drill bit, where the drilling fluid strikes and disintegrates the forming material in cooperation with the drill bit. An annular fluid having a density greater than that of the drilling fluid is continuously pumped into the annulus between the drill hole and the drill string, wherein the annular fluid substantially extends from the surface to the bottom of the drill string. The drilling fluid and cuts resulting from the disintegration of the forming material are returned to the surface through the substantially unobstructed tubular passage in the drill string. The annular fluid is maintained at a selected and controlled pressure, in which an intermediate surface is formed in the drill bit in which the annular fluid is mixed with the drilling fluid and is returned together with the drilling fluid and the cuttings, and the drilling fluid is prevented from entering the ring. According to the preferred embodiment of the present invention, the step of maintaining the annular fluid at a selected and controlled pressure further comprises selectively sealing the return flow of the drilling fluid, the cuts and the annular fluid on the surface to control the loss of the fluid. pressure through the shutter. The drilling fluid is also pumped to the drill string at a sufficient flow rate to maintain the intermediate surface between the drilling fluids and the ring as the drilling progresses. The selected and controlled pressure of the annular fluid and the shutter speed of the sealing fluid are monitored to ensure the maintenance of the intermediate surface between them in the drill bit. According to the preferred embodiment of the present invention, the method further comprises cutting the drilling fluid, including the drilling fluid and the cuts in the tubular passage, in the drill string on the surface and in the drill bit. A portion of drill pipe is connected to the drill string while it is closed and then the drill string is opened to continue drilling. According to the preferred embodiment of the present invention, the drilling fluid is pure water or clarified drilling mud and the annular fluid is a dense drilling mud, filter layer former. According to the preferred embodiment of the present invention, the drill string comprises a multi-conduit drill pipe having an outer tubular conduit for transmitting tension and torsion load. Means are provided at each end of the outer tubular conduit to connect the drill pipe to other sections of the drill pipe. At least one tubular conduit of reduced diameter for driving the high pressure fluid is arranged eccentrically within the tubular outer conduit. At least one tubular conduit of enlarged diameter is disposed eccentrically in the outer conduit and a sealing member is disposed therein to selectively obstruct the enlarged diameter tubular conduit. The closure member does not substantially restrict the diameter of tubular conduit of enlarged diameter in the open position. Other objects, features and advantages of the present invention will become apparent with reference to the detailed description that follows.

DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic representation of the method and apparatus according to the preferred embodiment of the present invention. Figure 2 is a logical flow diagram representing the steps of the method for controlling the method and apparatus according to the present invention. Figure 3 is a cross-sectional view of the multiple conduit drill pipe according to the preferred embodiment of the present invention. Figure 4 is a longitudinal sectional view, taken along line 4-4 of Figure 3, showing a portion of the drill pipe illustrated in Figure 4. Figure 5 is a longitudinal sectional view, to along the line 5-5 of Figure 3, which represents a portion of the drill pipe illustrated in Figure 4. Figures 6A-6H should be read together and are a longitudinal section and several cross-sectional views of the stabilizer of cross-section for use with the multi-conduit drill pipe according to the preferred embodiment of the present invention. Lae FIGS. 7A-7D should be read together and are a longitudinal section and several cross-sectional views of the lower bore assembly for use with the multiple conduit drill pipe and the cross stabilizer according to the preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION Referring now to the figures and specifically to Figure 1, a schematic representation of the method for drilling a hole according to the present invention is illustrated. A drill string 1, ending in a drill bit 3, is operated to a drill hole 5. A low density drilling fluid 3 or reduced solids content is pumped to drill string 1 through an inlet. 7 of the drilling fluid in the swivel. The drilling fluid may be pure water or clarified drilling mud, but it must have a lower density than conventional drilling mud and must have a reduced solids content to avoid abrasive wear. Preferably, the drilling fluid is water with solid matter no greater than 7 microns in size. The drilling fluid is preferably supplied to drilling rope 1 at a pumping pressure of 1406 kg / cm * - g in order to provide up to 3,200 horsepower of hydraulic power in drill 3. Water is brought under pressure through the drill string 1 at least through a conduit 9 of reduced diameter and high pressure that extends through the drill string, 1 and in communication with the fluid of the drill 3. A good seal is provided 11 at or near the bit 3 to avoid the reverse situation of the drilling fluid, as will be described in detail below. Concurrently with the supply of the high pressure drilling fluid through the inlet 7, a dense, ring-forming filter fluid is pumped to the ring between the drill string and the drill hole 5 through an inlet 13 of the annular fluid under a rotating projector 15 of explosions. The rotary explosion preventer 15 allows the drill string 1 to be rotated while maintaining the annular fluid under pressure selected and controlled. The annular fluid is a conventional drilling mud selected for its particular properties of the forming materials being drilled and other conventional factors. The annular fluid is pumped to the annulus continuously to maintain a column of annular fluid extending from the surface to the drill 3. The annular fluid must be continuously pumped to maintain this column as the perforation progresses. As described in more detail below, the pressures or injection or pumping rates of the high pressure drilling fluid and the annular fluid are controlled and monitored to maintain the intermediate surface between the drilling fluids and the ring in the drill bit. 3 so that drilling fluid is prevented from entering the ring and diluting the dense fluid, formed of filter layer. However, part of the annular fluid is allowed to mix with the drilling fluid and return to the surface through the return duct 17. The method according to the preferred embodiment of the present invention is specially adapted to be automated and controlled by computer using conventional data processing and control equipment. The hydraulic horsepower resulting from the supply of the high pressure drilling fluid in the drill 3 is combined with the conventional action of the drill 3 to disintegrate the formation material more efficiently. The drilling fluid and the cuts generated by the disintegration of the forming material are returned to the surface through a return passage 17, tubular, substantially unobstructed in the drill string 1. The term "substantially unobstructed" is used. "to indicate a generally straight tubular passage without substantial flow restrictions that is capable of flowing substantial amounts of fluid loaded with cuts and is easily cleaned if occlusion or occlusion occurs. The substantially unobstructed tubular passage 17 of the ring resulting from the concentric arrangements of the tube, which is susceptible to clogging and not easily cleaned in that case, is to be distinguished. The return flow of the drilling fluid and the cuts is selectively clogged at the surface by means of a sealing valve member 21 in the swivel to ensure maintenance on the intermediate surface between the drilling fluids of the drill ring 3. A ball valve 19 is provided in the duct 17 back at the end which is generally above the drill string 1 to facilitate the formation of new sections of pipe to the drill string 1. The drilling fluid of lower density present in the high-pressure duct 9 and the return duct 17 is especially susceptible to being expelled from the drill string 1, either by hydrostatic pressure of the annular fluid or of the forming pressures, especially when no pumping pressure is applied and when the flow back to conduit 17 is not completely obstructed, when the perforation is caused, the spherical valve is closed it was 19 on the surface, thereby closing the drilling fluid in conduit 17 back. The shut-off valve 11 combined with the hydrostatic pressure of the drilling fluid above it closes the high-pressure conduit 9. A new section of the drill pipe can then be added to the drill string 1 and a ball valve 19 is opened to restart the drilling. Before connecting a new section of the drill pipe to the drill string 1, at least the return pipe 17 must be filled with fluid to avoid a large pressure pulse when the ball valve 19 is opened. Similarly, it can be Have the drill surely for any reason, such as stopping the drill string 1 to change the drill 3 or for any similar purpose. Fig. 2 is a flow diagram showing the control of the fluids in the drill string 1 during the drilling operation 1 according to the method of the present invention. In block 51, the axial speed of drill string 1 is monitored. This is done by measuring the hook load exerted, and the axial position of the upper drive unit (not shown) that will rotate the drill string 1 during the drilling operation. According to the preferred embodiment of the present invention, the ring and drilling fluids are pumped as long as the drill string 1 is moving downwards, a condition associated with the drilling operation. Clearly, the ring and drilling fluids should be bonded during the downward movement of the rope associated with the drilling. In most operations, the only time it is not advantageous to pump one or both of the ring and drill fluids is how much drill string 1 is not moving and its velocity is 0. If the speed of the drill string is not equal to 0, At least the annular fluid is being pumped into the drilling hole. Preferably, the annular fluid is pumped automatically according to a multiple of the speed of the drill string 1 at all times that the speed of the drill string 1 is not equal to 0 and related drilling operations are occurring. Preferably, except as indicated below, the pumping of the drilling fluid is controlled manually by the operator. By having the drill string 1, the annular fluid is pumped into the drill hole at a speed sufficient to replace the volume of the drill hole that is no longer occupied by the drill string 1. In this way, the drill hole remains protected at all times. Thus, in block 53, if drill string 1 is moving, at least the annular fluid is being pumped into the drill hole. If the speed of the drill string 1 is positive, indicating drilling operation, both ring and drilling fluids are pumped to the drilling hole. The drilling fluid is pumped to drill string 1 at a pressure sufficient to generate 20 to 40 horsepower for every 6.45 c * of the bottom hole area at depths between 2134 and 4572 meters. Based on the dimensions of drill string 1 exposed in connection with Figures 3-7D, and other operating parameters, drilling fluid is supplied to drill string 1 on the surface at a pressure of 1406 kg / cm. * -gy and a flow rate of 821 l / min. The flow from the ring to the ring is pumped at a rate that continuously sweeps the annular fluid past the drill 3 as long as the drill string is moving axially. During normal drilling operations, this will maintain a continuous flow of the annular fluid beyond the periphery of the drill 3 and will not only keep the intermediate surface at the bottom of the drill hole, but will purge the ring from cuts or other waste. The injection velocity for the annular fluid is adjusted as a function of the axial upward velocity of the drill string 1. A preferred or typical injection speed is one that would keep the annular fluid moving at a speed that is twice that of the drill string 1. This pump or injection speed is maintained at all times as it is moving on drill string 1. In addition to the pump or injection speed, a selected positive pressure is maintained on the annular fluid on the surface and this pressure is controlled precisely below the rotary preventer of explosions. This selected pressure is not a single, discrete pressure, but rather a pressure scale, preferably between 4.22 and 4.92 kg / cm * -g. This pressure is monitored by a conventional pressure sensing device on the explosion preventer. To assure maintenance of the selected positive pressure, in block 55, the ring pressure is measured and compared to the selected pressure. If the ring pressure exceeds the selected pressure, the ring pressure is reduced. There are three options to reduce the ring pressure: 1) Open the shutter 21 on the return line 17 to reduce pressure loss through the shutter 21; 2) Reduce the speed of injection or pumping of the drilling fluid; and 3) Reduce the speed of injection or pumping of the annular fluid. Opening the shutter 21 is the preferred option to reduce the ring pressure to the selected scale. If this does not work, the speed of injection or pumping of the drilling fluid is reduced or it is automatically restricted, notwithstanding the speed of injection or pumping selected by the operator. As a final resource, the injection and pumping speed of the annular fluid is reduced below the selected speed based on the speed of the drill string. The reduction or restriction in the injection or pumping speed of the annular fluid is the last resort for the reduction of the ring pressure by the need to maintain a column of undiluted ring fluid that extends from the surface to the drill 3. Reducing the injection or pumping speed of the annular fluid as a last resort for reducing the ring pressure minimizes the risk that the drilling fluid will mix and dilute the annular fluid. In block 57, if the ring pressure is below the selected pressure, it increases, in block 61. There are three options to increase the ring pressure: 1) increase the speed of injection or pumping of the annular fluid again towards the selected speed; 2) increase the speed of injection or pumping of the drilling fluid up to the speed selected by the operator; and 3) close or restrict the obstruction 21 on the return line 17 to increase the pressure loss through the obstruction 21. The first option is carried out if the injection or pumping speed is, for some reason, insufficient for maintaining the speed of the annular fluid in excess of and preferably doubling the speed of the drill string 1. If the injection or pumping speed of the annular fluid is adequate, the second option can be carried out. However, it is contemplated that drilling fluid pumps operate at or near peak capacity and that significant increases in the speed of injection or pumping of drilling fluid may not be feasible. In this case, the third option of closing the obstruction or valve member 21 on the return line 17 is carried out. If the annular pressure is within the selected regime, no action is taken and the speed of the drill string 1 and the annular pressure are continuously monitored. If the drilling operations are stopped and / or the operator reduces the injection or pumping rates of the drilling fluid, the annular pressure will fall and the obstruction 21 will close automatically, effectively closing the drill string 1 and the hole until it is taken another action Figure 3 is a cross-sectional view of a section of a multiple conduit drill pipe 101 according to the preferred apparatus for practicing the method according to the present invention. The drill pipe 101 comprises an outer tube 103, which serves to support tensile and torsional loads applied to the drill pipe 101 during operation. Preferably, the outer tube 103 has an outer diameter of 19.37 mm and is made of API materials heat treated to obtain a resistance regime S135. A plurality of internal tubes are housed eccentrically and asymmetrically within the outer tubes 103 and serve as fluid transport conduits, electrical conduits and the like. These internal conduits include a return tube 105 of 8.90 mm outside diameter, which corresponds generally to the return tube 17 in Figure 1. Because the return tube 105 is not designed to carry fluids of extremely high pressure and for a Improved corrosion resistance, this is made of API material heat treated up to a LBO resistance regime. A pair of high pressure tubes 107 of 1.74 mm outer diameter are disposed in the outer tube 103 and correspond generally to the high pressure conduit 9 in Figure 1. Because the high pressure pipes 107 must carry extremely high pressure fluids. high, eetán formed of API material treated by heat until a resistance regime API S135. Other tubes 109 may be provided in the outer tube 102 to provide electrical conduits and the like. Tube 111 is not really a tube, but a portion of a check valve assembly that is described in greater detail with reference to Figure 5, below. Figure 4 is a longitudinal sectional view, taken along section line 4-4 of Figure 3, illustrating a p >of drill pipes 101 in accordance with the present invention secured to one another. As can be seen, the outer tube 103, the return tube 105 and the high pressure tube 107 are secured by means of threads to an upper end member 113. The upper end member 113 is similarly formed to a conventional tool joint and includes a bottom seal ball valve 115 of outside diameter of 8.90 mm and a rate of 703 kg / cm3 * gauge, in general alignment with the return tube 105. The ball valve 115 has an internal diameter of approximately 1.74 mm and does not present a substantial obstruction or flow restriction in the return tube 105. The ball valve 115 corresponds to the valve or closure member 19 in Figure 1.

The lower end of the outer tube 113 is secured by means of threads to a lower end member 117, which is also generally formed as a conventional tool joint. A sealing ring 119 is received in the lower end member 117 and if it rivets to seal the inside of the piercing tube 101 against the return tube 105 and the high pressure tubes 107. A plurality of split rings 121 engage with circumferential grooves. in the return tube 105 and the high pressure tubes 107, and are confined in the lower end member 117 by means of securing rings 123, 125 and outer tube 103. The split ring 121 and the securing rings 123 and 125 serve to contract the inner tubes against relative axial movement towards the rest of the drill pipe .1.01. Or unless the inner tubes of the tube 101 are secured against axial movement at each end of the drill tube, the tubes will be excessively distorted due to high pressure fluids and vibrations during operation. After constituting the sections of the drill pipe 101, the lower ends of the inner tubes (only the return tube 105 and the high pressure tube 107 are illustrated) are received in the upper end member 113 and sealed by means of seals Conventional Elastomerics A securing ring 123 mechanically couples together the threaded connections of the upper end members 113 e 77 bottom 117. The lower end member 117 is provided with threads of a larger pitch diameter than those of the upper end member 113 so that the lock ring 127 can be completely decoupled from the lower end member 117 being carried at the same time by the threads. on the upper end member 113. The threads on the securing ring 127 are formed to generate an axial contact force of approximately 373,000 kilograms between the upper end members 113 and lower end 117. Preferably, each section of the drill pipe 10.1 is 13.7 meters of length. Figure 5 is a longitudinal sectional view, taken along section 5-5 of Figure 3, illustrating a check valve arrangement by means of which downward fluid communication can be established between the defined ring between the inner tubes 105, 107 and the outer tube 103 of drill pipe 101. A check valve assembly is disposed in a hole in the upper end member 113. The check valve comprises a conventional valve member 129 biased upwardly. by means of spiral spring 131 to allow fluid to flow down through drill pipe 101, but not upwards. A check valve arrangement in a similar manner is provided in the lower end member 117. The check valve assembly includes a lifting member 133 and a spiral spring 135 carried in a sleeve 111, which is attached to the end member. bottom 119 is between the return tube 105. Unlike the check valve member in the upper end member 113, the purpose of the check valve assembly in the lower end member 119 is to prevent fluid loss from the inside of the drill pipe 101 when two sections are uncoupled. After forming the two sections, an extension of the lift valve 131 engages a projection or flange 137 on the upper end member 113, opening the lift valve 131 and allowing fluid communication between the interior of the outer tube 1.03 of successive sections of the drill pipe 101. With this check valve arrangement, the interior or annular portion of the outer tubes 103 can be filled with annular fluid or the like, and the fluid communication can be established downstream of a direction. through the outer tubes 103. This fluid communication is necessary to equalize the pressure differential between the inside and the outside of the drill pipe 101 in depth. Equalization is achieved by pumping a small amount of fluid into the inner ring of drill string 101, which is communicated down through the check valves to equalize the pressure. Figures 6A-6H are to be seen as a whole and are sectional views of a transition stabilizer 201 for use with the drill pipe or drill string 101 in accordance with the preferred embodiment of the present invention. In Figure 6A is a longitudinal sectional view, while Figures 6B-6H are transverse views, taken along the length of Figure 6A in the corresponding section line of transition stabilizer 201. Transition stabilizer 201 It is formed from a single piece of non-magnetic material to avoid interference with the measuring equipment during drilling ("MUD"). The transition stabilizer 201 is coupled to the lower end of a section of the drill pipe 101 generally as described with reference to Figures 4 and 5. A plurality of holes 205, 207 are formed through the transition stabilizer 201 and correspond to high pressure pipes 107 and return valve 105 of drill pipe 101, as shown in Figure 6B. A transition port 211 is formed in the side wall of one of the high pressure holes 207 for communicating high pressure drilling fluid from one of the holes 207 to the other, as illustrated in Figure dC. A retractable shutter 213 is provided in one of the holes 207 below the port 211 to block the hole 207, as shown in Figure 6D. The remainder of the hole 207 below the shutter 213 houses a conventional directional and retractable MLJD apparatus. The obturator 213 serves to prevent the high pressure drilling fluid from impacting the MUD apparatus. Under the plug 213, the holes 205 and 207 are reduced in diameter to provide a space for another high pressure drilling fluid hole 213 generally disposed opposite the hole 207, as shown in Figure 6E. As shown in Figure 6F, a transition hole 215 connects the hole 207 with the hole 213 so that the high pressure drilling fluid is carried by a hole 207 and another 213, which are disposed generally opposite each other. The arrangement of the holes 207, 213 opposite one another tends to neutralize any bending moment generated by the high pressure fluids carried in the holes. As described above, another hole 207 houses a MUD apparatus, as shown in Figure 6G. The transition stabilizer 201 is connected to the uppermost portion of a bottom hole assembly 301 comprising a section of drill pipe generally similar to that described with reference to Figures 4 and 5, but with internal tubes arranged to correspond to holes 205, 207, 213 of the transition stabilizer 201, as shown in Figure 6H. Figures 7A-7D are sectional views of a bottom hole assembly 301 and drill bit 401 according to the preferred embodiment of the present invention. Figure 7A is a longitudinal sectional view of the bottom hole assembly 301 and drill bit 401. Figures 7B-7D are cross-sectional views, taken along the length of Figure 7A and corresponding to the section lines of the assembly. 301 and drill bit 401. As seen with reference to Figs. 7A and 7B, the bottom hole assembly 301 includes an upper outer tube 303A, which is coupled to the transition stabilizer 201 as described in connection with Figs. 4 and 5. A lower tube of elongated diameter 303B is coupled to the upper outer tube 303B to provide more space in the bottom hole assembly 301. The lower outer tube 303B is threaded at its lowest point to receive internal tubes 307 and 313, which they maintain the opposite disposition established by the transition stabilizer 201. The return tube 305 is sealingly coupled with the lower outer tube 303B to allow rotation and facilitate assemble A port 315 is provided in the sidewall of the return tube 305 and is in fluid communication through a check valve assembly 317, similar to those described in connection with Figure 5, with the inner ring defined between the lower outer tube 303B and the tubes ported therein. In this way, the fluid coming from this inner ring can be pumped into the return tube 305 from the inner ring, while preventing the fluid in the return tube 305 from entering the inner ring. A solenoid-operated flap valve 319 is disposed in the return tube 305 and has a velocity of 703 kg / cm * gauge to maintain pressure under the valve 319. The flap valve 319 is closed to trap fluid in the tube. return 305 when the drill string is disengaged 1. A pair of check valves 321 is disposed in pairs. the p >The lower portion of the lower outer tube 303B in communication with high pressure tubes 307, 313. As described with reference to Fig. 1, the check valves 321 prevent reverse circulation of drilling fluid upward in the high pressure tubes 307, 313. An extension of the return tube 323 is threaded towards the lower portion of the lower outer tube 303B in fluid communication with the return tube 305. A drill 401 of the fixed cutting variety is secured by a pin and box connection conventional threaded towards lowermost end portion of lower outer tube 303B. The drill 401 includes a drill face 405 having a plurality of hard cutters, preferably diamond cutters disposed thereon in a conventional arrangement. A p > regreeo 405 ee extends through the drill 401 from an eccentric portion of the drill face 403 into fluid communication with the extension of the 323 regree tube and the return tube 305 piara to establish the return conduit for the fluid of perforation, lae shear and the ring fluid mixed with the same. Four high-spaced passageways 407 diametrically spaced extend through the drill 401 and intersect a generally transvereal passage 409, which is obstructed by a welded, screwed or fixed plug 4.1.1. A plurality of nozzles 413 extend from transverealee passages 409 to pour high pressure drilling fluid to the bottom of the hole. Preferably, the total flow area of the nozzles 413 is 0.258 c *. Preferably the bit is a 23.07 mm gauge bit used in conjunction with the drill pipe 101 with outside diameter of 20 m. The method and apparatus according to the present invention has a number of advantages. In addition, the present invention provides an apparatus method for drilling with a reduced solids content drilling fluid while maintaining a dense fluid of filter cake buildup in the rings as drilling progresses. The method and apparatus are more commercially practicable than previous attempts. Additionally, the method according to the present invention is particularly adapted to be automated and computer controlled. The invention has been described with reference to the preferred embodiment thereof. Therefore, it is not limited but it is susceptible to modification and variation without departing from the scope and spirit of the invention.

Claims (24)

NOVELTY OF THE INVENTION CLAIMS

1. - A method for drilling a hole comprising the steps of: activating a drill string that ends in a drill bit inside a hole; pumping a drilling fluid of reduced solids content through the drill string and out of the drill bit, where the drilling fluid collides and disintegrates forming material in cooperation with the drill; continuously pumping an annular fluid with a density greater than that of the drilling fluid into a ring between the hole and the drill string, while drilling the forming material, wherein the annular fluid substantially extends from the surface to the bottom of the bit; returning the drilling fluid and cuts resulting from the disintegration and formation of material to the surface through a tubular passage not substantially obstructed in the drill string; and maintaining the annular fluid under a selected pressure in a ring where the interface is formed in the drill bit wherein the ring fluid is mixed with the drilling fluid and is returned together with the drilling fluid and the cuttings and Substantially, drilling fluid is prevented from entering the ring.

2. - The method according to claim 1, wherein the step of maintaining the annular fluid under a selected pressure comprises in addition to the steps of: selectively obstructing the return flow of return fluid, cuts and annular fluid on the surface to control the loss of pressure through the obstruction; pumping the drilling fluid into the drill string and out of the drill bit at a flow rate sufficient to maintain the interface of the ring and drilling fluid as drilling progresses; and monitor the selected pressure of the annular fluid and the filling of the drilling fluid.

3. The method according to claim 1, which further comprises the steps of: closing the drilling fluid, including the drilling fluid and cuts in the tubular passage, in the drill string on the surface and in the drill; connecting a length of the drill pipe inside the drill spring while the drill spring is closed; and open the drill spring to continue drilling.

4. The method according to claim 1, wherein the drilling fluid is clear water.

5. The method according to claim 1 wherein the drilling fluid is clarified drilling mud.

6. The method according to claim 1, wherein the annular fluid is a dense drilling mud of filter cake accumulation.

7. A method for drilling a hole comprising the steps of: activating within a hole a drill string that includes at least one high-pressure conduit and at least one tubular return conduit inside the drill string , finishing the drill string on a drill bit; pumping a drilling fluid of reduced solids content through the high-pressure conduit and out of the brocade, where the drilling fluid collides and disintegrates the formation material in cooperation with the drill; continuously pumping n annular fluid having a greater density than that of the drilling fluid into a ring between the hole and the drill string while drilling forming material, wherein the annular fluid substantially extends from the surface to the the bottom of the bit; returning the drilling fluid and the resulting cuts from the disintegration of the formation material and the excess annular fluid to the surface through the tubular regreeo conduit in the drill string; maintain the annular fluid under an selected pressure in the ring, where the interface is formed in the drill bit in which the annular fluid mixes with the drilling fluid and is returned together with the fluid and the puncture cuts, but Substantially preventing drilling fluid from entering the ring; Periodically close the drilling fluid in the drill string on the surface and on the drill bit; subsequently connecting a length of the drill pipe into the drill string while the drill string is closed; and subsequently open the drill string to continue drilling.

8. The method according to claim 7, wherein the closing step comprises: closing a valve member in the return conduit of the drill string on the surface; and closing a valve member in the high-pressure conduit of the drill string proximate to the drill, wherein substantially all of the fluid in the drill string is prevented from coming out of the drill string.

9. The method according to claim 7, wherein the step of maintaining the annular fluid under a selected pressure further comprises the steps of: selectively obstructing the return duct in the surface to control the loss of pressure through the obturation; and pumping drilling fluid into the high pressure conduit and out of the drill at a flow rate sufficient to maintain the selected pressure and the interface between the annular and drilling fluid as drilling progresses; and monitoring the selected pressure of the annular fluid and the filling of the drilling fluid.

10. The method according to claim 7, wherein the drilling fluid is clear water.

11. The method according to claim 7, wherein the drilling fluid is clarified drilling mud.

12. The method according to claim 7, wherein the annular fluid is a dense drilling mud of filter cake accumulation.

13. A method for drilling a hole comprising the p > asos: operating a drill string in a hole that includes at least one high-pressure duct and at least one tubular return duct inside the drill string, ending the drilling chord in a drill bit; pump a drilling fluid of reduced solids content through the high-pressure conduit and out of the drill bit, where the drilling fluid will strike and disintegrate forming material in cooperation with the drill; maintain an annular fluid having a density higher than that of the drilling fluid at a selected pressure in a ring between the drill string and the hole, by pumping a drilling fluid into the high-pressure conduit and the annular fluid into the annulus flow velocities sufficient to maintain a gap between the drilling and annular fluid as the drilling progresses; regreear the drilling fluid and the cuts resulting from the disintegration of the formation material towards the surface through the tubular return conduit in the drill string, wherein a gap between the drilling and annular fluid is formed in the drill bit, which substantially prevents drilling fluid from entering the ring; Selectively clog the duct back to the surface to control the loss of pressure through the obstruction; and monitor selected pressure, obstruction and flow regimes.

14. The method according to claim 13, further comprising the steps of; Periodically close the drilling fluid in the drill string on the surface and on the drill bit; subsequently connecting a length of the drill pipe into the drill string while the drill string is closed; and open the drill string sub-echelonly to continue drilling.

15. The method according to claim 14, wherein the closing action comprises: closing a valve member in the return duct of the drill string at the surface; and closing a valve member in the high-pressure conduit of the drill string proximate to the drill, wherein substantially all of the fluid in the drill string is prevented from coming out of the drill string.

16. The method according to claim 7, wherein the drilling fluid is clear water.

17. The method according to claim 13, wherein the drilling fluid is clarified drilling mud.

18. - The method according to claim 13, wherein the annular fluid is a dense drilling mud of filter cake accumulation.

19. The method according to claim 13, wherein the purpose of maintaining the annular fluid at a selected pressure further comprises the step of: electively alternating the flow rate at which the drilling fluid is pumped into. of the drill string.

20. A multiple conduit drilling pipe for the production of earth formations, the drill pipe comprising: an outer tubular conduit for transmitting torsional load; means at each end of the tubular outer conduit for connecting the drill pipe to other similar sections of the drill pipe; at least a small diameter tubular conduit for driving high pressure fluid through the drill pipe; the tubular conduit of reduced diameter being arranged eccentrically in the tubular outer conduit; at least one tubular conduit of elongated diameter having a larger diameter than that of the tubular conduit of reduced diameter, the tubular conduit having an elongated diameter arranged eccentrically in the outer tubular conduit; and a closure member disposed in the elongated diameter tubular conduit for selectively obstructing the elongated diameter tubular conduit, the closure member does not contract substantially the diameter of the elongated diameter tubular conduit in an open position.

21. The multiple conduit drilling pipe according to claim 20 further comprising: a pair of tubular conduits of reduced diameter; an electrical conduit arranged eccentrically in the outer tubular conduit for carrying an electrical conductor in the drill pipe.

22. The multiple conduit drilling pipe according to claim 20, wherein the closing member is a ball valve operable from the outside of the drill pipe.

23. The multiple conduit drilling pipe according to claim 20, in each of the conduits arranged in the outer tubular conduit is secured in each extrusion thereof to the external tubular conduit.

24. The multiple conduit drilling pipe according to claim 20 further comprising: a closing member at each end of the outer tubular conduit that is closed when the drill pipe is not connected to another section of the drill pipe, but it is open when the drill pipe is connected to another section of the drill pipe having a corresponding reduced diameter tubular conduit.