A method for reaming while drilling in ultra-deep well composite salt formation

Abstract

An embodiment of the present invention provides a method for reaming while drilling in a ultra-deep well composite salt layer. The method includes: selecting at least one reamer, at least one drill bit, and at least one drill collar assembly; constructing at least one drill string assembly with the reamer, the drill bit, and the drill collar assembly; and using at least one of the drill string assemblies to drill a composite formation. It is possible to perform reaming while drilling in the ultra-deep well composite salt layer section, eliminate the sticking caused by the creep and diameter reduction in the salt layer section, and reduce the post-drilling reaming process. Therefore, the problems of poor drilling safety, low efficiency, and slow exploration and development progress in the prior art when drilling in the composite salt layer section are solved.

Description

Technical Field

[0001] The present invention relates to the field of drilling engineering, and in particular to a method for reaming while drilling in ultra-deep well composite salt formations. Background Art

[0002] With the rapid development of society, the demand for energy has increased significantly. The petrochemical energy in shallow formations can no longer meet the needs of society. Therefore, it has become an inevitable trend to develop petrochemical energy in deeper formations, and more and more sub-salt oil and gas reservoirs have been developed. As the well depth increases, the drilling difficulty will also increase accordingly. In such sub-salt oil and gas reservoirs, salt formations have always been a world drilling problem due to their strong plasticity, low compressive strength, and fast creep rate. Especially for ultra-deep well composite salt formation sections with high temperature and high pressure characteristics, the drilling difficulty is even greater. Due to the high degree of creep and hole shrinkage in the composite salt formation section, severe sticking occurs during the drilling process, and it is necessary to increase the density of the drilling fluid to slow down the creep rate of the salt formation. However, the composite salt formation contains mudstone and sandstone with low compressive capacity, and using high-density drilling fluid is likely to cause lost circulation during drilling and cementing. This results in a narrow drilling fluid density window, complex drilling, and extremely easy to cause accidents, seriously affecting drilling safety and production efficiency. The creep of the composite salt formation section will cause difficulties in running casing. Before running casing, it is necessary to measure the creep rate of the salt formation statically, repeatedly ream the hole to break the hole shrinkage section, and even need to perform post-drilling reaming operations, resulting in a long completion operation time and seriously affecting production efficiency.

[0003] Currently, when using oil-based drilling fluid for drilling, the problem of swelling and collapse of inter-salt mudstone due to water absorption is eliminated, and the drilling safety has been improved to a certain extent, but the problem of hole shrinkage due to salt formation creep still exists. When using a conventional drill string assembly for drilling, the density of the drilling fluid is 2.10 - 2.50 g / cm 3 , and every 150 - 300 m of drilling or continuous drilling for 2 days, it is necessary to make a short trip to break the hole shrinkage of the salt formation; for the hole shrinkage section, it is necessary to repeatedly ream the hole to eliminate it to ensure safety. According to incomplete statistics, about 1 / 3 of the wells have lost circulation during drilling and cementing in the composite salt formation section, and the complex treatment time for lost circulation accounts for about 6 - 10%; in the drilling efficiency, the time for short trips and reaming to deal with hole shrinkage in the salt formation accounts for about 5 - 15% of the total time. After drilling the composite salt formation section, in some wells, due to the high degree of salt formation creep, it is difficult to run casing, and it is easy to cause casing lifting accidents. Usually, it is necessary to use the method of measuring the creep rate of the salt formation statically after completion to determine whether it is safe to run casing. If the creep rate of the salt formation is fast, it is necessary to repeatedly ream the hole to break the hole shrinkage section, and even need to perform post-drilling reaming. The post-drilling reaming time generally takes 7 - 10 days (slightly different according to different well depths).

[0004] However, the above drilling methods have poor drilling safety and low efficiency, affecting the exploration and development progress. Summary of the Invention

[0005] In order to solve the problems of poor drilling safety, low efficiency, and slow exploration and development progress during the drilling of composite salt formations in the prior art, the present invention provides a method for reaming while drilling in ultra-deep well composite salt formations.

[0006] The present invention provides a method for reaming while drilling in ultra-deep well composite salt formations, including:

[0007] Select at least one reamer, at least one drill bit, and at least one drill collar assembly;

[0008] Construct the reamer, the drill bit, and the drill collar assembly into at least one drill string assembly;

[0009] Drill the composite formation with at least one of the drill string assemblies.

[0010] In a specific embodiment of the present invention, the drilling of the composite formation with at least one of the drill string assemblies includes:

[0011] Drill the composite salt formation section of the composite formation with the first drill string assembly in at least one of the drill string assemblies, with a weight on bit of 80 - 120 kN and a rotational speed of 60 - 80 rpm;

[0012] Drill the salt bottom geological interlayer section of the composite formation with the second drill string assembly in at least one of the drill string assemblies, with a weight on bit of 50 - 100 kN and a rotational speed of 60 - 80 rpm.

[0013] In a specific embodiment of the present invention, the construction of the reamer, the drill bit, and the drill collar assembly into at least one drill string assembly includes:

[0014] Construct the first reamer in the at least one reamer, the first drill bit in the at least one drill bit, and the first drill collar assembly and the second drill collar assembly in the at least one drill collar assembly into the first drill string assembly;

[0015] Construct the second reamer in the at least one reamer, the second drill bit in the at least one drill bit, and the third drill collar assembly in the at least one drill collar assembly into the second drill string assembly;

[0016] Wherein, the outer diameter of the cutter blade of the first reamer is greater than the outer diameter of the first drill bit, the outer diameter of the cutter blade of the second reamer is greater than the outer diameter of the second drill bit, and the outer diameter of the first drill bit is greater than the outer diameter of the second drill bit.

[0017] In a specific embodiment of the present invention, the construction of the first reamer in the at least one reamer, the first drill bit in the at least one drill bit, and the first drill collar assembly and the second drill collar assembly in the at least one drill collar assembly into the first drill string assembly includes:

[0018] Connect one end of the first drill bit to one end of the first drill collar assembly;

[0019] Connect the other end of the first drill collar assembly to one end of the first reamer;

[0020] Connect the other end of the first reamer to one end of the second drill collar assembly to form the first drill string assembly.

[0021] In a specific embodiment of the present invention, constructing the second reamer in the at least one reamer, the second drill bit in the at least one drill bit, and the third drill collar assembly in the at least one drill collar assembly into the second drill string assembly includes:

[0022] Connect one end of the second drill bit to one end of the second reamer;

[0023] Connect the other end of the second reamer to one end of the third drill collar assembly to form the second drill string assembly.

[0024] In a specific embodiment of the present invention, it further includes:

[0025] Select a first centralizer and downhole motor. The downhole motor includes a vertical drilling tool or a positive displacement motor. The outer diameter of the first centralizer is smaller than the outer diameter of the first drill bit;

[0026] Constructing the first reamer in the at least one reamer, the first drill bit in the at least one drill bit, the first drill collar assembly and the second drill collar assembly in the at least one drill collar assembly into the first drill string assembly includes:

[0027] Connect one end of the first drill bit to one end of the downhole motor;

[0028] Connect the other end of the downhole motor to one end of the first centralizer;

[0029] Connect the other end of the first centralizer to one end of the first drill collar assembly;

[0030] Connect the other end of the first drill collar assembly to one end of the first reamer;

[0031] Connect the other end of the first reamer to one end of the second drill collar assembly to form the first drill string assembly;

[0032] It further includes: Select a second centralizer. The outer diameter of the second centralizer is smaller than the outer diameter of the second drill bit;

[0033] Construct the second drill string assembly from the second reamer in the at least one reamer, the second drill bit in the at least one drill bit, and the third drill collar assembly in the at least one drill collar assembly, including:

[0034] Connect one end of the second drill bit to one end of the second reamer;

[0035] Connect the other end of the second reamer to one end of the second centralizer;

[0036] Connect the other end of the second centralizer to one end of the third drill collar assembly to form the second drill string assembly.

[0037] In a specific embodiment of the present invention, after constructing the drill string assembly, it further includes:

[0038] Test the drill string assembly;

[0039] The testing of the drill string assembly includes:

[0040] Wind tape on the cutter blades of the reamer;

[0041] Connect the reamer to the top drive or the kelly bar and lower the reamer below the rotary table surface;

[0042] Start the pump and gradually increase the displacement at a constant speed to the designed displacement, and stop the pump after stabilizing the displacement for 2 - 5 minutes;

[0043] Lift the reamer above the rotary table surface for inspection. If the tape is intact, the reamer is normal. If the tape falls off, replace the drill string assembly and re - test the drill string assembly.

[0044] In a specific embodiment of the present invention, the drilling of the composite salt layer section of the composite formation using the first drill string assembly in the at least one drill string assembly includes:

[0045] After each drill pipe is drilled by the first drill string assembly, perform back - reaming treatment using the first drill string assembly, and the back - reaming rotation speed of the first drill string assembly is 50 - 60 r / min, and the drilling pressure is 10 - 20 kN;

[0046] Judge whether the wellbore is unobstructed;

[0047] If the wellbore is unobstructed, control the first drill string assembly to perform downward reaming at a speed higher than the back - reaming speed and continue to drill the composite salt layer to monitor the torque during reaming and drilling;

[0048] If the wellbore is obstructed, control the first drill string assembly to perform repeated reaming until the wellbore is unobstructed.

[0049] In a specific embodiment of the present invention, after drilling the composite salt layer section of the composite formation using the first drill string assembly among the at least one drill string assembly, the following steps are further included:

[0050] Determine whether the bit in the first drill string assembly has drilled to the salt gypsum formation marker layer in the composite salt layer section;

[0051] If it has drilled to the marker layer, pull out the first drill string assembly and replace it with the second drill string assembly;

[0052] If it has not drilled to the marker layer, continue to drill using the first drill string assembly.

[0053] In a specific embodiment of the present invention, before drilling the composite salt layer section of the composite formation using the first drill string assembly among the at least one drill string assembly, the following steps are further included:

[0054] Place the first drill string assembly in the casing;

[0055] Determine whether the reamer in the first drill string assembly is at least 5 meters below the casing shoe;

[0056] If it is, control the first drill string assembly to start drilling;

[0057] If not, continue to lower the first drill string assembly.

[0058] The present invention provides a method for reaming while drilling in a ultra-deep well composite salt layer, which at least includes selecting at least one reamer, at least one bit and at least one drill collar assembly, and constructing the reamer, the bit and the drill collar assembly into at least one drill string assembly. Since the drill string assembly includes both a bit and a reamer, the purpose of reaming while drilling can be achieved. Therefore, when drilling the composite formation with at least one such drill string assembly, reaming while drilling in the ultra-deep well composite salt layer section can be realized, the sticking caused by creep and diameter reduction in the salt layer section is eliminated, and the post-drilling reaming process is reduced. Thus, the problems of poor drilling safety, low efficiency and slow exploration and development progress in the prior art when drilling the composite salt layer section are solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0060] Figure 1 It is a schematic structural diagram of the first drill string assembly in an embodiment of the present invention;

[0061] Figure 2 It is a schematic structural diagram of the second drill string assembly in the embodiment of the present invention;

[0062] Figure 3 It is a flowchart of the method for reaming while drilling in the ultra-deep well composite salt layer in the embodiment of the present invention;

[0063] Figure 4 It is a flowchart of testing the drill string assembly in the embodiment of the present invention;

[0064] Figure 5 It is a flowchart of drilling in the composite salt layer section in the embodiment of the present invention;

[0065] Figure 6 It is a flowchart of drilling in the salt bottom geological layer clamping section in the embodiment of the present invention.

[0066] Description of the reference numerals:

[0067] 10 - First drill string assembly;

[0068] 101 - First drill bit;

[0069] 102 - Downhole motor drill;

[0070] 103 - First centralizer;

[0071] 104 - First drill collar assembly;

[0072] 105 - First reamer;

[0073] 106 - Second drill collar assembly;

[0074] 20 - Second drill string assembly;

[0075] 201 - Second drill bit;

[0076] 202 - Second reamer;

[0077] 203 - Second centralizer;

[0078] 204 - Third drill collar assembly. Detailed implementation manners

[0079] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0080] This embodiment provides a method for reaming while drilling in ultra-deep well composite salt formations, which is mainly applied to the drilling in ultra-deep well composite salt formation sections and the drilling for geological sticking at the salt bottom. The composite formation is drilled by a drill string assembly equipped with a reamer, so as to realize the reaming operation while drilling, eliminate the sticking caused by creep and diameter reduction in the salt formation section, reduce the post-drilling reaming process, and improve the drilling safety and efficiency.

[0081] See Figure 3 As shown, this embodiment provides a method for reaming while drilling in ultra-deep well composite salt formations. The method specifically includes the following steps:

[0082] S101. Select at least one reamer, at least one bit, and at least one drill collar assembly.

[0083] In this embodiment, the number of reamers can be one, or two or more.

[0084] In this embodiment, two reamers are selected, namely the first reamer 105 and the second reamer 202.

[0085] In this embodiment, the number of bits can be one, or two or more.

[0086] In this embodiment, two bits are selected, namely the first bit 101 and the second bit 201.

[0087] In this embodiment, the number of drill collar assemblies can be one, or two or more.

[0088] In this embodiment, three drill collar assemblies are selected, namely the first drill collar assembly 102, the second drill collar 106, and the third drill collar 204.

[0089] S102. Construct at least one drill string assembly with the reamer, bit, and drill collar assembly.

[0090] In this embodiment, at least one drill string assembly is constructed with the reamer, bit, and drill collar assembly. For example, one drill string assembly is constructed with the reamer, bit, and drill collar assembly, or two or more drill string assemblies are constructed with the reamer, bit, and drill collar assembly.

[0091] In this embodiment, two drill string assemblies are constructed with the reamer, bit, and drill collar assembly, namely the first drill string assembly 10 and the second drill string assembly 20.

[0092] S103. Drill the composite formation with at least one drill string assembly.

[0093] In this embodiment, the composite formation is drilled with one drill string assembly, or the composite formation is drilled with two or more drill string assemblies.

[0094] In this embodiment, two drill tool combinations are used to drill the complex formation, and the two drilling combinations are the first drill tool combination 10 and the second drill tool combination 20 respectively.

[0095] The present invention provides a method for reaming while drilling in a ultra-deep well composite salt layer, which includes at least selecting at least one reamer, at least one drill bit and at least one drill collar assembly, and constructing the reamer, drill bit and drill collar assembly into at least one drill tool combination. Since the drill tool combination includes both a drill bit and a reamer, the purpose of reaming while drilling can be achieved. Therefore, when using at least one such drill tool combination to drill the complex formation, reaming while drilling in the ultra-deep well composite salt layer section can be realized, the sticking caused by creep and diameter reduction in the salt layer section is eliminated, and the post-drilling reaming process is reduced. Therefore, the problems of poor drilling safety, low efficiency and slow exploration and development progress in the prior art when drilling in the composite salt layer section are solved.

[0096] In this embodiment, constructing the reamer, drill bit and drill collar assembly into at least one drill tool combination includes the following steps:

[0097] Step A1, constructing the first reamer 105 in at least one reamer, the first drill bit 101 in at least one drill bit, the first drill collar assembly 104 and the second drill collar assembly 106 in at least one drill collar assembly into the first drill tool combination 10;

[0098] Step B1, constructing the second reamer 202 in at least one reamer, the second drill collar 201 in at least one drill bit and the third drill collar assembly 204 in at least one drill collar assembly into the second drill tool combination 20.

[0099] For example, when constructing the first drill tool combination 10 and the first drill tool combination 10, refer to Figure 1 as shown, the first reamer 105 in at least one reamer, the first drill bit 101 in at least one drill bit, the first drill collar assembly 104 and the second drill collar assembly 106 in at least one drill collar assembly can be constructed into the first drill tool combination 10. Refer to Figure 2 as shown, the second reamer 202 in at least one reamer, the second drill collar 201 in at least one drill bit and the third drill collar assembly 204 in at least one drill collar assembly can be constructed into the second drill tool combination 20.

[0100] In this embodiment, the first drill bit 101 is a PDC drill bit, and the outer diameter of the first drill bit 101 is smaller than the inner diameter of the upper casing.

[0101] In this embodiment, the outer diameter of the cutter wing of the first reamer 105 is larger than the outer diameter of the first drill bit 101.

[0102] In this embodiment, the working outer diameter of the cutter blades of the first reamer 105 is 1 to 1.5 inches (25.4 to 38.1 mm) larger than the outer diameter of the first drill bit 101.

[0103] In this embodiment, the first drill collar assembly 104 is composed of 1 to 2 drill collars, the second drill collar assembly 106 is composed of 12 to 18 drill collars, and the distance between the first reamer 105 and the first drill bit 101 is about 30 m.

[0104] In this embodiment, an MWD measurement-while-drilling instrument is also installed inside the drill collars of the first drill collar assembly 104 for measuring downhole drill string attitude information such as tool face, well inclination, and azimuth.

[0105] In this embodiment, the second drill bit 201 uses an aggressive PDC drill bit, and the outer diameter of the second drill bit 201 is smaller than the inner diameter of the upper casing.

[0106] In this embodiment, the outer diameter of the cutter blades of the second reamer 202 is larger than the outer diameter of the second drill bit 201.

[0107] In this embodiment, the working outer diameter of the cutter blades of the second reamer 202 is 1 to 1.5 inches (25.4 to 38.1 mm) larger than the outer diameter of the first drill bit 101.

[0108] In this embodiment, the third drill collar assembly 204 is composed of 12 to 18 drill collars. For example, the third drill collar assembly 204 can be composed of 15 drill collars, or in some examples, the third drill collar assembly 204 can be composed of 16 drill collars. In this embodiment, the number of drill collars included in the third drill collar assembly 204 is specifically selected according to actual requirements.

[0109] In this embodiment, the outer diameter of the first drill bit 101 is larger than the outer diameter of the second drill bit 201, and the outer diameter of the cutter blades of the first reamer 105 is larger than the outer diameter of the cutter blades of the second reamer 202.

[0110] In this embodiment, both the first reamer 105 and the second reamer 202 are controllable hydraulically opened type, and the reamers are activated by ball dropping or displacement method.

[0111] In this embodiment, when constructing the first drill string assembly 10 with the first reamer 105 in at least one reamer, the first drill bit 101 in at least one drill bit, and the first drill collar assembly 104 and the second drill collar assembly 106 in at least one drill collar assembly, the following steps are specifically included:

[0112] Step A2: Connect one end of the first drill bit 101 to one end of the first drill bit assembly 104;

[0113] Step B2: Connect the other end of the first drill collar assembly 104 to one end of the first reamer 105;

[0114] Step C2: Connect the other end of the first reamer 105 to one end of the second drill collar assembly 106 to form the first drill string assembly 10.

[0115] In this embodiment, when constructing the second drill string assembly 20 from the second reamer 202 in at least one reamer, the second drill collar 201 in at least one bit, and the third drill collar assembly 204 in at least one drill collar assembly, the following steps are specifically included:

[0116] Step A3: Connect one end of the second bit 201 to one end of the second reamer 202;

[0117] Step B3: Connect the other end of the second reamer 202 to one end of the third drill collar assembly 204 to form the second drill string assembly 20.

[0118] In this embodiment, a corresponding downhole motor 102 and a first centralizer 103 can be added to the first drill string assembly 10. The downhole motor 102 includes a vertical drilling tool or a positive displacement motor.

[0119] In this embodiment, for some wells with large formation dip angles and prone to well deviation, a vertical drilling tool can be added to the first drill string assembly 10; for directional wells due to trajectory control requirements, a positive displacement motor can be added to the first drill string assembly 10.

[0120] In this embodiment, the first centralizer 103 can improve the stability of the first drill string assembly 10 during drilling.

[0121] In this embodiment, the first centralizer 103 and the downhole motor 102 are selected. The downhole motor 102 includes a vertical drilling tool or a positive displacement motor, and the outer diameter of the first centralizer 103 is smaller than the outer diameter of the first bit 101.

[0122] In this embodiment, constructing the first drill string assembly 10 from the first reamer 105 in at least one reamer, the first bit 101 in at least one bit, the first drill collar assembly 104, and the second drill collar assembly 106 in at least one drill collar assembly includes the following steps:

[0123] Step A4: Connect one end of the first bit 101 to the downhole motor 102;

[0124] Step B4: Connect the other end of the downhole motor 102 to one end of the first centralizer 103;

[0125] Step C4: Connect the other end of the first centralizer 103 to one end of the first drill collar 104;

[0126] Step D4: Connect the other end of the first drill collar 104 to one end of the first reamer 105;

[0127] Step E4: Connect the other end of the first reamer 105 to one end of the second drill collar assembly 106 to form the first drill string assembly 10.

[0128] In this embodiment, to further improve the stability during drilling, 1 - 2 centralizers can be added to the second drill collar assembly 106.

[0129] In this embodiment, a second centralizer 203 can be added to the second drill string assembly 20.

[0130] In this embodiment, the second centralizer 203 can improve the stability of the second drill string assembly 20 during drilling.

[0131] In this embodiment, the second centralizer 203 is selected, and the outer diameter of the second centralizer 203 is smaller than the outer diameter of the second drill bit 201;

[0132] In this embodiment, the second reamer 202 in at least one reamer, the second drill collar 201 in at least one drill bit, and the third drill collar assembly 204 in at least one drill collar assembly are constructed into the second drill string assembly 20, including the following steps:

[0133] Step A5: Connect one end of the second drill bit 201 to one end of the second reamer 202;

[0134] Step B5: Connect the other end of the second reamer 202 to one end of the second centralizer 203;

[0135] Step C5: Connect the other end of the second centralizer 203 to one end of the third drill collar assembly 204 to form the second drill string assembly 20.

[0136] In this embodiment, to further improve the stability during drilling, 1 - 2 centralizers can be added to the third drill collar assembly 204.

[0137] In this embodiment, both the first centralizer 103 and the second centralizer 203 are spiral. The outer diameter of the first centralizer 103 is 1 / 8 inch (3.17 mm) smaller than the size of the first drill bit 101; the outer diameter of the second centralizer 203 is 1 / 8 inch (3.17 mm) smaller than the size of the second drill bit 201.

[0138] In this embodiment, the size matching of the drill bit and other tools can refer to the following table:

[0139] Serial number Bit outer diameter (mm) Reamer blade outer diameter (mm) Centralizer (mm) Discharge rate (l / s) 1 333.37 368.3～406.4 328～329 40～60 2 311.1 336.6～381 306～307 20～50 3 241.3 266.7～279.4 237～238 18～40 4 215.9 228.6～260.4 211～212 15～35 5 168.3 177.8～190.5 163～164 12～20 6 152.4 165.1～177.8 147～148 10～15

[0140] In this embodiment, after forming the drill string assembly, that is, after the above step S102, it also includes testing the constructed drill string assembly. Refer to Figure 4 As shown, testing the drill string assembly includes the following steps:

[0141] S201. Wind the tape on the cutter blades of the reamer.

[0142] S202. Connect the reamer to the top drive or the kelly, and lower the reamer below the rotary table surface.

[0143] S203. Start the pump and gradually increase the displacement at a uniform speed to the designed displacement, and stop the pump after stabilizing the displacement for 2 - 5 minutes.

[0144] S204. Lift the reamer above the rotary table surface for inspection to determine whether the tape is intact.

[0145] S205. If the tape is intact, it is determined that the reamer is normal.

[0146] S206. If the tape has fallen off, replace the drill string assembly and re - conduct the drill string assembly test.

[0147] In this embodiment, at least one drill string assembly is used to drill the complex formation, including the following steps:

[0148] Step A6. Use the first drill string assembly 10 in at least one drill string assembly to drill the composite salt layer section of the complex formation, with a weight on bit of 80 - 120 kN and a rotary speed of 60 - 80 rpm.

[0149] Step B6. Use the second drill string assembly 20 in at least one drill string assembly to drill the salt bottom geological interlayer section of the complex formation, with a weight on bit of 50 - 100 kN and a rotary speed of 60 - 80 rpm.

[0150] In this embodiment, as shown in Figure 5 Use the first drill string assembly 10 in at least one drill string assembly to drill the composite salt layer section of the complex formation, specifically including the following steps:

[0151] S305. After the first drill string assembly 10 has drilled one drill pipe, conduct backreaming with the first drill string assembly 10, and the backreaming rotary speed of the first drill string assembly 10 is 50 - 60 r / min, and the weight on bit is 10 - 20 kN.

[0152] S306. Judge whether the wellbore is unobstructed.

[0153] S307. If the wellbore is unobstructed, control the first drill string assembly 10 to conduct downward reaming at a rotary speed higher than the backreaming speed, and continue to drill the composite salt layer to monitor the torque during reaming and reaming.

[0154] S308. If the wellbore is obstructed, control the first drill string assembly 10 to conduct repeated reaming until the wellbore is unobstructed.

[0155] In this embodiment, as shown in Figure 5As shown, after drilling the composite salt layer section of the composite formation using the first drill string assembly 10 in at least one drill string assembly, the following steps are further included:

[0156] S309. Determine whether the bit in the first drill string assembly 10 has drilled to the gypsum formation marker layer in the composite salt layer section;

[0157] S3010. If it has drilled to, then pull out the first drill string assembly 10 and replace the first drill string assembly 10 with the second drill string assembly 20;

[0158] S3011. If it has not drilled to, then continue to drill using the first drill string assembly 10.

[0159] In this embodiment, referring to Figure 5 As shown, before drilling the composite salt layer section of the composite formation using the first drill string assembly in at least one drill string assembly, the following steps are further included:

[0160] S301. Place the first drill string assembly in the casing;

[0161] S302. Determine whether the reamer in the first drill string assembly is at least 5 meters below the casing shoe;

[0162] S303. If so, control the first drill string assembly to start drilling;

[0163] S304. If not, then continue to lower the first drill string assembly.

[0164] In this embodiment, referring to Figure 6 As shown, drilling the salt bottom geological marker layer section of the composite formation using the second drill string assembly 20 in at least one drill string assembly specifically includes the following steps:

[0165] S401. Drill the salt bottom geological marker layer section using the second drill string assembly 20;

[0166] S402. Determine the formation according to the drilling rate, and stop drilling for geological circulation when the drilling rate slows down;

[0167] S403. Determine whether it is the salt bottom formation according to the cuttings returned;

[0168] S404. If it is the salt bottom formation, then stop drilling;

[0169] S405. If it is not the salt bottom formation, then continue to drill until reaching the salt bottom.

[0170] Taking the Φ241.3mm wellbore of the deep well in Kuqa, Tarim as an example, the specific engineering application of this application is described:

[0171] The first drill string assembly is for use when drilling in the upper composite salt formation section. Considering the large formation dip angle in the Kuqa area, to prevent deviation and drill quickly, a vertical drilling tool and an MWD measurement-while-drilling instrument are installed in the first drill string assembly.

[0172] The specific composition of the first drill string assembly is: Φ241.3mm bit + vertical drilling tool + Φ238mm centralizer + 1 Φ178mm drill collar (with an MWD measurement-while-drilling instrument installed inside) + 1 Φ178mm drill collar + reamer (blade opening Φ279mm) + Φ178mm drill collar string (12 - 18 pieces).

[0173] The second drill string assembly is designed for the need of geological sticking at the bottom of the salt layer and the safety of running casing during completion. The reamer is installed as close to the bit as possible to ensure that the unreamed section is as short as possible, making it a near-bit measurement-while-drilling reaming drill string assembly.

[0174] The specific composition of the second drill string assembly is: Φ215.9mm bit + reamer (blade opening Φ266.7mm) + 1 Φ178mm drill collar + Φ238mm centralizer + Φ178mm drill collar string (12 - 18 pieces).

[0175] The outer diameters of the bit and the reamer in the second drill string assembly are respectively smaller than those of the bit and the reamer in the first drill string assembly. This is beneficial for safe running of the drill string and reduces the time for reaming and scraping the hole.

[0176] The bit nozzles are W12*3 + W13*2, TFA: 0.61in 2 ;

[0177] The weight on bit is 50 - 120kN (judge the formation according to the penetration rate, the weight on bit in the composite salt formation section is 80 - 120KN, and the weight on bit in the geological sticking section at the bottom of the salt layer is 50 - 100KN); the rotary speed is 80rpm, the drilling displacement is 22 - 25L / s, and the torque limit of the top drive is 28kN.m;

[0178] When drilling in the composite salt formation section, use the first drill string assembly. Start construction after the reamer blades are at least 5 meters below the casing shoe. First, pump balls to build pressure to activate the reamer, and then start drilling. After drilling each single drill pipe, backream once to check the wellbore. If the wellbore is unobstructed, connect a single drill pipe and continue drilling.

[0179] During drilling, closely monitor the torque during reaming and backreaming. The actual situation of downhole reaming and formation creep can be judged by the friction during short trips / round trips. Determine whether the drilling fluid density is appropriate. When drilling to dolomite (the marker bed of the salt gypsum formation in the Tarim area), pull out of the hole and replace with the second drill string assembly.

[0180] For the salt-bottom geological bedding section, the second drill string assembly is adopted. During drilling, pay attention to observing the changes in drilling time and torque. When slow drilling time is detected, perform geological circulation. Determine whether it is the salt-bottom formation based on the cuttings returned. If it is the salt-bottom formation, stop drilling; if not, continue drilling until reaching the bottom of the hole.

[0181] Meanwhile, during drilling, well-watching should be carried out well to promptly detect well leakage. Once well leakage is detected, immediately stop the pump and promptly lift the drill string, lifting the bit to the reamed hole section.

[0182] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for reaming while drilling in ultra-deep well composite salt formation, characterized in that The method includes: Selecting at least one reamer, at least one drill bit, and at least one drill collar assembly; Connecting one end of the first drill bit to one end of the first drill collar assembly; Connecting the other end of the first drill collar assembly to one end of the first reamer; the first drill collar assembly is composed of 1 to 2 drill collars; Connecting the other end of the first reamer to one end of the second drill collar assembly to form a first drill string assembly; the second drill collar assembly is composed of 12 to 18 drill collars; Connecting one end of the second drill bit to one end of the second reamer; the outer diameter of the first drill bit is greater than the outer diameter of the second drill bit; the outer diameter of the cutter blades of the first reamer is greater than the outer diameter of the cutter blades of the second reamer; Connecting the other end of the second reamer to one end of the third drill collar assembly to form a second drill string assembly; the third drill collar assembly is composed of 12 to 18 drill collars; Using the first drill string assembly in the at least one drill string assembly to drill the composite salt layer section of the composite formation, with a drilling pressure of 80 to 120 kN and a rotational speed of 60 to 80 rpm; Using the second drill string assembly in the at least one drill string assembly to drill the salt bottom geological interlayer section of the composite formation, with a drilling pressure of 50 to 100 kN and a rotational speed of 60 to 80 rpm; The using the first drill string assembly in the at least one drill string assembly to drill the composite salt layer section of the composite formation includes: After the first drill string assembly drills one drill pipe, performing back reaming with the first drill string assembly, and the back reaming rotational speed of the first drill string assembly is 50 to 60 r / min, and the drilling pressure is 10 to 20 kN; Judging whether the wellbore is unobstructed; If the wellbore is unobstructed, controlling the first drill string assembly to perform downward reaming at a rotational speed higher than the back reaming rotational speed and continue drilling the composite salt layer to monitor the torque during reaming and drilling; If the wellbore is obstructed, controlling the first drill string assembly to perform repeated reaming until the wellbore is unobstructed.

2. The ultra-deep well complex salt bed under-reaming method according to claim 1, characterized in that: The outer diameter of the cutter blades of the first reamer is greater than the outer diameter of the first drill bit, and the outer diameter of the cutter blades of the second reamer is greater than the outer diameter of the second drill bit.

3. The ultra-deep well complex salt bed under-reaming method according to claim 2, wherein It further includes: Selecting a first centralizer and a downhole motor drill, the downhole motor drill includes a vertical drilling tool or a positive displacement motor, and the outer diameter of the first centralizer is less than the outer diameter of the first drill bit; The constructing the first drill string assembly from the first reamer in the at least one reamer, the first drill bit in the at least one drill bit, the first drill collar assembly and the second drill collar assembly in the at least one drill collar assembly includes: Connecting one end of the first drill bit to one end of the downhole motor drill; Connecting the other end of the downhole motor drill to one end of the first centralizer; Connecting the other end of the first centralizer to one end of the first drill collar assembly; Connecting the other end of the first drill collar assembly to one end of the first reamer; Connecting the other end of the first reamer to one end of the second drill collar assembly to form the first drill string assembly; It further includes: selecting a second centralizer, and the outer diameter of the second centralizer is less than the outer diameter of the second drill bit; Constructing the second drill string assembly from the second reamer among the at least one reamer, the second drill bit among the at least one drill bit, and the third drill collar assembly among the at least one drill collar assembly includes: Connecting one end of the second drill bit to one end of the second reamer; Connecting the other end of the second reamer to one end of the second centralizer; Connecting the other end of the second centralizer to one end of the third drill collar assembly to form the second drill string assembly.

4. The ultra-deep well composite salt layer under-reaming method according to any one of claims 1-3, characterized in that: After constructing the drill string assembly, it further includes: Testing the drill string assembly; The testing of the drill string assembly includes: Wrapping tape around the cutter blades of the reamer; Connecting the reamer to the top drive or the kelly and lowering the reamer below the drill floor; Starting the pump and gradually increasing the displacement at a constant speed to the designed displacement, and stopping the pump after stabilizing the displacement for 2 - 5 minutes; Lifting the reamer above the rotary table for inspection. If the tape is intact, the reamer is normal; if the tape has fallen off, replace the drill string assembly and re - conduct the drill string assembly test.

5. The under-reaming method while drilling in ultra-deep well composite salt formation according to any one of claims 1-3, characterized in that: After drilling the composite salt layer section of the composite formation using the first drill string assembly among the at least one drill string assembly, it further includes: Judging whether the drill bit in the first drill string assembly has drilled to the salt gypsum formation marker bed in the composite salt layer section; If it has drilled to it, pull out the first drill string assembly and replace the first drill string assembly with the second drill string assembly; If it has not drilled to it, continue to drill using the first drill string assembly.

6. The ultra-deep well complex salt bed under-reaming method according to any one of claims 1-3, characterized in that: Before drilling the composite salt layer section of the composite formation using the first drill string assembly among the at least one drill string assembly, it further includes: Placing the first drill string assembly in the casing; Judging whether the reamer in the first drill string assembly is at least 5 meters below the casing shoe; If so, control the first drill string assembly to start drilling; If not, continue to lower the first drill string assembly.

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