A segmented plugging removal stimulation and packing sand prevention method for horizontal well casing non-cementing completion

Abstract

The present application relates to a kind of segmented plugging and production increasing and packing sand prevention method for horizontal well casing not cementing completion, the method comprises the following steps: S1, the horizontal section of production casing is divided into well section;S2, hydraulic sandblasting perforation stimulation operation;S3, sand filling is blocked in pipe to the section that has been perforated;S4, annulus gravel packing sand prevention operation;S5, repeat the operation of step S2 to S4 to the n+1 section, and so on, until the N section is completed operation;S6, reverse sand washing well flushing operation.The method provided by the present application combines hydraulic perforation plugging and production increasing and gravel packing sand prevention operation process, utilizes operation string to implement segmented operation to horizontal well, and using a string can realize production increasing and sand prevention integrated operation, greatly improves operation efficiency.

Description

Technical Field

[0001] This invention relates to the field of loose sandstone reservoir development technology, specifically to a segmented unblocking and sand-control method for horizontal well casing uncemented completion. Background Technology

[0002] Loose sandstone oil and gas reservoirs are widely distributed and often characterized by shallow burial, poor lithology, loose cementation, and high porosity and permeability. Due to the large pore throats in loose sandstone reservoirs, drilling and completion fluids are prone to leakage into the reservoir matrix during drilling and completion, causing near-wellbore reservoir damage, resulting in a large skin coefficient, and affecting single-well productivity and production stability. Furthermore, due to the loose cementation of loose sandstone reservoirs, the formation is susceptible to severe sand production during production, which negatively impacts normal oil and gas well production and even the overall development of the oil and gas field. Therefore, low production capacity and reservoir sand production are among the prominent problems restricting the efficient development of loose oil and gas reservoirs.

[0003] Gravel packing sand control technology is one of the advanced well completion technologies, characterized by its outstanding sand control effect and long effective period, especially for fine sand, and it can effectively control the production capacity of oil wells. However, conventional gravel packing cannot meet the needs of unblocking and increasing production, especially for gravel packing in long horizontal wells. Due to the long open hole section, conventional gravel packing is prone to settling and forming sand bridges, which can prematurely interrupt the gravel packing process, resulting in low annular gravel packing rate, poor sand control effect, and short sand control life.

[0004] For example, the existing technology (Ma Mingxin. Horizontal well segmented gravel packing technology and field application[J]. Petroleum Machinery, 2014, 42(7):5.) introduces the structure and working principle of horizontal well open hole segmented gravel packing tubing, the main gravel packing tools - new gravel packing composite sand control screen, packing packer and packing and washing assembly, and describes the application of horizontal well segmented gravel packing technology.

[0005] CN103266869A discloses a horizontal well segmented gravel packing service tool, including an outer casing and an inner core. The inner core is equipped with at least two linkage mechanisms, each including a support rod and a working arm. One end of the working arm is rotatably connected to the side wall of the outer casing via a first pin, and the other end of the working arm is rotatably connected to one end of the support rod via a second pin. The other end of the support rod is rotatably connected to the inner core via a third pin. When the inner core moves along the axis of the outer casing towards the other end of the inner core, the other end of the working arm can rotate outward about the first pin and extend beyond the outer surface of the outer casing. One such segmented packing service tool can cooperate with various levels of segmented packing tools and can control any segment of the horizontal well segmented gravel packing tool, achieving effective switching of each level of segmented packing tools. It is easy to operate and has stable performance.

[0006] While the aforementioned packing techniques or gravel packing services can perform gravel packing on horizontal wells, they cannot prevent near-wellbore reservoir damage. Therefore, how to prevent drilling and completion fluid from entering the reservoir matrix and causing near-wellbore reservoir damage, while simultaneously preventing reservoir sand production from adversely affecting normal production, is a technical problem that needs to be solved. Summary of the Invention

[0007] To address the above problems, the present invention aims to provide a segmented unblocking and production enhancement and sand control method for horizontal well casing uncemented completion. Compared with the prior art, the method provided by the present invention combines hydraulic perforation unblocking and production enhancement with gravel filling and sand control operations. It utilizes the working tubing string to carry out segmented operations on the horizontal well, and can achieve integrated production enhancement and sand control operations with a single tubing string, greatly improving the efficiency of construction operations.

[0008] To achieve this objective, the present invention adopts the following technical solution: This invention provides a method for staged unclogging and sand control in horizontal well casing uncemented completions, the method comprising the following steps: S1, divide the horizontal section of the production casing into well sections; The horizontal segment from the end point B to the target entry point A is divided into segments 1, 2, ..., N, where N ≥ 2; S2, water jet perforation for increased production; A multi-cluster hydraulic sandblasting perforation operation is carried out on the nth production casing using a working tubing, where 1≤n<N; along the direction from point B to point A, the first cluster of perforations, the second cluster of perforations, ..., the mth cluster of perforations are obtained sequentially, where m≥2; S3, filling the pipe with sand to seal the perforated section; The working tubing is used to fill the nth section with sand to form a sand plug inside the tubing, thus sealing the perforation holes of the first to the (m-1)th clusters, while leaving the perforation holes of the mth cluster unsealed. S4, Circumferential gravel backfilling for sand control; The filling fluid carrying gravel is injected into the annulus between the tubing and the production casing of the working tubing string. The filling fluid enters the annulus between the production casing and the open hole through the perforation holes of the nth section and the mth cluster, where gravel remains. The filling fluid enters the sand plug inside the tubing through the perforation holes of the nth section from the 1st cluster to the m-1st cluster, and then returns to the surface through the tubing. S5. Repeat steps S2 to S4 for the (n+1)th segment, and so on, until the Nth segment is completed. S6, reverse sand flushing and well cleaning operation.

[0009] The method provided in this invention uses a working tubing string for hydraulic perforation for enhanced production, sand plugging, and gravel packing. To improve the gravel packing effect, considering the heterogeneous characteristics of horizontal wells, the horizontal well section is divided into several segments. The horizontal well is divided into N segments from the end point B of the horizontal segment to the target point A, with a segment length generally of 50-80m. The segment closest to point B is segment 1, and the segment closest to point A is segment N. Based on this, hydraulic perforation for enhanced production, sand plugging, and gravel packing operations are performed on segments 1 to N, respectively.

[0010] Preferably, before dividing the horizontal section of the production casing into well sections, a completion string is used to complete the target well.

[0011] Preferably, the completion string includes a production casing and a casing hanger.

[0012] In this invention, the production sleeve can be a conventional sleeve in the art, such as a production sleeve made of N80 or P110 material between 5-1 / 2″ and 9-5 / 8″.

[0013] In this invention, the casing hanger can be a conventional casing hanger in the art, such as a hanger matched to the production casing and wellhead, or the previous completion casing, used to suspend the production casing and seal the annulus outside the production casing. In this invention, the production casing is suspended near the wellhead or the previous completion casing shoe by the casing hanger.

[0014] Preferably, the working string includes a tubing guide shoe, a check valve, a nozzle sub, a packer, a safety joint, and tubing arranged sequentially along the direction from point B to point A.

[0015] In this invention, the tubing can be a commonly used tubing in the art, selected according to the specifications of the production casing and construction parameters, thereby ensuring that the requirements for liquid injection and return are met during construction.

[0016] In this invention, the main function of the safety joint is to provide an emergency release measure for the working string after it gets stuck in the well, ensuring that the working string can be successfully pulled out under complex working conditions.

[0017] In this invention, the purpose of the one-way valve is to control the unidirectional flow of fluid. When the oil is injected into the pipe, it is injected directly through the nozzle section without passing through the one-way valve. However, the fluid can flow back into the pipe through the one-way valve.

[0018] In this invention, the nozzle section is composed of a wear-resistant alloy jet nozzle and an anti-splash spray gun body, wherein the nozzle structure, quantity, phase, etc. are designed according to the actual construction operation requirements.

[0019] In this invention, the packer is a mechanically seated and unsealable packer, such as the Y221 packer commonly used in the art. The packer is seated and anchored by rotating it forward and compressing it after the working string is lifted, and the packer is unsealable by lifting the working string.

[0020] In this invention, the tubing guide shoe is used to guide the working tubing string smoothly into the well to the designed well section.

[0021] Preferably, step S2 specifically includes the following steps: S21, lower the working tubing into the nth segment of the production casing; S22, starting from the end of the nth segment near point B, performs multi-cluster hydraulic sandblasting perforation to penetrate the production casing and connect the reservoir.

[0022] Preferably, the multi-cluster hydraulic jet perforation operation includes: pumping perforation fluid carrying abrasive material through tubing, injecting it into the production casing through a nozzle sub, performing hydraulic jet perforation through annular backflow between the tubing and the production casing, establishing a hydraulic jet channel in the near-wellbore reservoir, and performing m hydraulic jet perforation operations on the nth section by raising the tubing. Each hydraulic jet perforation operation forms a cluster of perforations, wherein the mth cluster of perforations in the nth section is denoted as P. n-m .

[0023] In this invention, multi-cluster hydraulic jet perforation can penetrate the production casing, connect the reservoir, and establish large-diameter, deep-penetrating hydraulic jet channels in the near-wellbore reservoir. The channel depth must be greater than the reservoir contamination radius.

[0024] Preferably, the viscosity of the perforating fluid is 20~30 mPa·s, for example, it can be 20 mPa·s, 22 mPa·s, 24 mPa·s, 26 mPa·s, 28 mPa·s or 30 mPa·s, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0025] Preferably, the abrasive comprises quartz sand.

[0026] Preferably, the abrasive ratio is 5-7%, for example, it can be 5%, 5.5%, 6%, 6.5% or 7%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0027] Preferably, the orifice velocity of the nozzle section is 180~210m / s, for example, it can be 180m / s, 185m / s, 190m / s, 195m / s, 200m / s, 205m / s, 210m / s, 215m / s or 210m / s, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0028] Preferably, the single-cluster perforation time for the water jet perforation operation is 10-15 minutes, for example, it can be 10 minutes, 12 minutes, 14 minutes or 15 minutes, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0029] In this invention, the perforating fluid is a low-viscosity, anti-swelling perforating fluid, requiring good compatibility between the perforating fluid and the reservoir. The abrasive is commonly used in the art, such as 40 / 70 quartz sand.

[0030] Preferably, the spacing between adjacent perforations is 8 to 10 m, for example, it can be 8 m, 9 m or 10 m, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0031] In this invention, the number of perforations (cluster number) is related to the length of the nth segment and the distance between the perforations. By controlling the distance between the perforations, it can be ensured that the perforation channels between perforation clusters do not interfere with each other.

[0032] Preferably, step S3 specifically includes the following steps: S31, lower the working string into the first cluster perforation hole of the nth segment, i.e., P. n-1 Around, and make the nozzle short section of the working tube stagger the injection hole; S32, using a tubing pump to inject sedimentation fluid, which is then injected into the production casing through a nozzle short section. The fluid is flushed back through the annulus between the tubing and the production casing, forming an internal sand plug within the production casing. The work string is then dragged to seal the perforations from the first cluster to the (m-1)th cluster in the nth segment, i.e., P. n-1 To P n-(m-1) And the mth cluster aperture is P n-m Do not block it.

[0033] Preferably, the settling liquid includes ceramsite.

[0034] Preferably, the density of the ceramsite is 1.5~1.8 g / cm³. 3 For example, it could be 1.5g / cm³ 31.6g / cm 3 1.7g / cm 3 Or 1.8g / cm 3 However, this does not limit the listed values; other unlisted values ​​within the range are also applicable.

[0035] Preferably, the sand ratio of the ceramsite is ≥50%, for example, it can be 50%, 60% or 70%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0036] In this invention, an oil pipe is used at a low discharge rate (0.5~1.0m). 3 Injecting a high-sand-ratio settling fluid at a rate of ( / min) can fill the wellbore with sand to form a high-permeability internal sand plug. The settling fluid uses medium-density ceramsite (density 1.5~1.8 g / cm³). 3 After flowing out through the nozzle short section, the annular flow velocity decreases and sedimentation occurs, forming a highly permeable sand plug inside the wellbore with extremely high permeability.

[0037] In this invention, the settling solution is required to have good compatibility with the reservoir, with a viscosity generally of 1 mPa·s, comparable to that of water. The particle size of the ceramsite is generally ≥12 / 20 mesh, and the density of the ceramsite is 1.5~1.8 g / cm³. 3 The sand ratio of the ceramsite is ≥50%. The flow velocity of the sediment in the tubing is greater than the critical sand-carrying velocity in the tubing, but less than the critical sand-carrying velocity in the annulus between the tubing and the production casing. At the same time, the erosion of the casing wall by the sediment when it exits the nozzle short section is also considered.

[0038] It should be noted that, in order to prevent the tubing from being buried in sand during the sand filling process, the tubing is required to move slightly up and down after the sand-laden fluid flows out from the nozzle section. Once the amount of sand filling meets the sealing requirements, the tubing is slowly raised to the next perforation cluster until the sealing of the first to m-1 perforation clusters in the nth section is completed. During implementation, it is inevitable that a small amount of ceramic particles will enter the annulus between the production casing and the open hole through the perforations. This small amount of ceramic particles will not affect the subsequent gravel filling operation.

[0039] Preferably, step S4 specifically includes the following steps: S41, seal the packer seat of the working string to the perforation holes of the nth segment from the mth cluster to the (m-1)th cluster, i.e., P. n-m To P n-(m-1) between; S42, filler fluid carrying gravel is injected into the annulus between the tubing and the production casing. The filler fluid carrying gravel passes through the m-th perforation hole in the nth segment, i.e., P. n-mThe gravel enters the annulus between the production casing and the open hole, thereby performing gravel packing operations in the annulus of the production casing and the open hole, as well as in the hydraulic jet channel. Under the action of the sand plug inside the casing, the gravel remains in the annulus of the production casing and the open hole. The packing fluid passes through the perforations from the first cluster to the (m-1)th cluster in the nth section, i.e., P... n-1 To P n-(m-1) The sand plug enters the pipe and passes through the nozzle stub and check valve of the working tubing into the tubing, then returns to the surface; S43. When the injection pressure reaches the desanding pressure, stop the injection, release the packer, use the tubing pump to inject displacement fluid, and inject it into the production casing through the nozzle sub. Displace the filling fluid in the annulus of the tubing and production casing out of the wellhead, thus completing the construction.

[0040] In this invention, the working tubing is dragged to P. n-m To P n-(m-1) A packer is placed between the tubing and production casing, and gravel-laden packing fluid is injected into the annulus between the tubing and production casing to perform gravel packing between the nth production casing and the open hole. Simultaneously, gravel is packed into the jet channel to form a stable gravel packing layer, effectively controlling sand. During operation, the annulus between the tubing and production casing, and the perforation hole P... n-m A gravel-filled channel is formed, while the extremely high permeability sand plugs inside the production casing, the nozzle short section of the work string, and the check valve create a backflow channel for the filling fluid. This transforms the function of the work string into a sand-filled return string, where the liquid phase of the filling fluid flows through P... n-1 To P n-(m-1) The sand plug enters the pipe and then passes through the nozzle stub and check valve of the working tubing before returning to the surface.

[0041] In this invention, during the gravel filling process, as gravel accumulates in the annulus between the production casing and the open hole, the filling pressure slowly increases. The sand ratio can be appropriately reduced to continue filling. When the nth stage achieves saturated filling, the injection pressure reaches the desanding pressure and the injection is stopped. The tubing string is lifted to release the packer, and the filling fluid is displaced out of the wellhead by injecting displacement fluid through the tubing, thus completing the nth stage construction.

[0042] Preferably, the gravel comprises resin balls.

[0043] Preferably, the density of the gravel is 1.00~1.20 g / cm³. 3 For example, it could be 1.00 g / cm³. 3 1.05g / cm 3 1.10 g / cm 3 1.15g / cm 3 Or 1.20g / cm 3 However, this does not limit the listed values; other unlisted values ​​within the range are also applicable.

[0044] Preferably, the gravel has a sand ratio of 5-15%, for example, 5%, 6%, 8%, 10%, 12%, 14% or 15%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0045] In this invention, low-density resin balls are generally used as gravel, and their particle size is selected according to the sand particle size produced by the reservoir. The sand ratio of the gravel is 5~15%, and the filling and discharging volume is determined according to the formation fracture pressure, etc. It is required that the bottom hole pressure is less than the formation fracture pressure during the gravel filling process.

[0046] Preferably, the filling fluid is infused with fibers.

[0047] Preferably, the fiber content in the filling liquid is 5-10% by mass, for example, it can be 5%, 6%, 8% or 10%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0048] In this invention, to protect the reservoir, the filling fluid must have good compatibility with the reservoir, and its viscosity is generally 1~10 mPa·s. To ensure the filling effect of the gravel, for low-temperature natural gas hydrate reservoirs (temperature 10~20℃), 5~10% fiber is generally injected into the filling fluid to form a spatial network structure in the gravel filling layer, improving the quality of the gravel filling layer; for high-temperature conventional oil and gas reservoirs (temperature ≥60℃), in addition to fiber injection, the gravel can also be made of solidifiable resin balls, utilizing the high temperature of the reservoir to achieve solidification between the filling gravel, which can also form a high-quality gravel filling layer.

[0049] In this invention, after step S4 is completed, the working tubing is dragged to the (n+1)th segment, and the operation is repeated according to steps S2 to S4 until the operation of all well segments in the horizontal section is completed.

[0050] Preferably, step S6 specifically includes the following steps: S61, replace the working tubing with a clear oil tubing and lower it into the production casing; S62 utilizes the annulus of the bare tubing and production casing to inject flushing fluid, which is then returned from the bare tubing until the sand plug inside the tubing from point A to point B is flushed out, clearing the wellbore before well production begins.

[0051] In this invention, the working tubing is lifted up, the clear oil tubing is replaced and lowered, and a reverse sand flushing operation is adopted, that is, sand flushing fluid is injected from the annulus between the clear oil tubing and the production casing, and returns from inside the clear oil tubing.

[0052] Preferably, the annulus of the clear oil pipe and the production casing is alternately injected with low-viscosity sand-washing fluid and high-viscosity sand-washing fluid.

[0053] Preferably, the viscosity of the low-viscosity sand flushing fluid is 10~20 mPa·s, for example, it can be 10 mPa·s, 12 mPa·s, 14 mPa·s, 16 mPa·s, 18 mPa·s or 20 mPa·s, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0054] Preferably, the viscosity of the high-viscosity sand flushing fluid is 50~100 mPa·s, for example, it can be 50 mPa·s, 60 mPa·s, 70 mPa·s, 80 mPa·s, 90 mPa·s, or 100 mPa·s, but is not limited to the listed values; other unlisted values ​​within the range are also applicable. In this invention, for efficient sand flushing, low-viscosity and high-viscosity sand flushing fluids are generally pumped alternately. The sand plug inside the casing is flushed from point A to point B, and after clearing the wellbore, production can begin.

[0055] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a method for segmented unblocking and production enhancement and gravel filling for sand control in horizontal well casing uncemented completion. It integrates hydraulic perforation unblocking and production enhancement, gravel filling for sand control, downhole tools, well run-in materials, and tubing annulus channels. It proposes a process method for perforation unblocking and production enhancement, temporary wellbore sealing, annulus gravel filling, and wellbore backwashing unblocking, realizing the integrated technology of segmented unblocking and production enhancement and gravel filling for sand control in horizontal wells. A single tubing string can be used to carry out integrated segmented unblocking and production enhancement and gravel filling operations in horizontal wells, which greatly improves the efficiency of construction operations. Attached Figure Description

[0056] Figure 1 This is a schematic diagram of the process for increasing production through water jetting perforation provided in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the process for sand control operation by filling annular gravel with sand according to Embodiment 1 of the present invention; Figure 3 This is a schematic diagram illustrating the effect of the ring-shaped gravel filling sand control operation provided in Embodiment 1 of the present invention; Figure 4 yes Figure 3 A magnified view of a section at point A in the middle; Figure 5 yes Figure 3 A magnified view of a section at point B.

[0057] Among them, 1-open hole; 2-production casing; 3-casing hanger; 4-tubing; 5-safety joint; 6-packer; 7-nozzle sub; 8-check valve; 9-tubing guide shoe; 10-hydraulic jet channel; 11-ceramsite; 12-resin ball; 13-fiber. Detailed Implementation

[0058] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0059] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0060] Example 1 This embodiment provides a method for staged unclogging and production enhancement and sand control in horizontal well casing uncemented completion, such as... Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 As shown. Taking a loose sandstone reservoir as the research object, a horizontal well was completed using a 5-1 / 2″ N80 production casing 2 without cementing, with a completion depth of 2000m and a horizontal section length of 300m. A casing hanger 3 was used to suspend the production casing 2 at the wellhead within the open hole 1. During drilling, the drilling fluid caused some damage to the near-wellbore zone of the reservoir, resulting in a high skin coefficient, necessitating unblocking and stimulation to increase production capacity. Furthermore, due to the loose reservoir and low cementation strength, severe sand production occurred during production, requiring sand control considerations during completion. To simultaneously achieve unblocking production and sand control requirements, the method described in this embodiment includes the following steps: S1, divide the horizontal section of production casing 2 into well sections.

[0061] Based on the heterogeneous characteristics of horizontal wells, the section from the end point B to the target point A is divided into six segments: segment 1, segment 2, ..., segment 6. The segments are: segment 1 1950-2000m, segment 2 1900-1950m, segment 3 1850-1900m, segment 4 1800-1850m, segment 5 1750-1800m, and segment 6 1700-1750m.

[0062] S2, water jetting and perforation for increased production.

[0063] Along the direction from point B to point A, assemble the tubing guide shoe 9, check valve 8, nozzle sub 7, packer 6, safety joint 5, and tubing 4 in sequence to obtain the working tubing string.

[0064] S21, lower the working tubing into the first section of the production casing 2.

[0065] S22, based on the engineering geological characteristics of the horizontal well reservoir, the spacing of each cluster of perforations is set to 10m. Starting from the end of the first section closest to point B, five clusters of hydraulic sandblasting perforations are performed on the first section to penetrate the production casing 2, sequentially obtaining the first cluster of perforations, the second cluster of perforations, ..., the fifth cluster of perforations, denoted as P. 1-1 P 1-2 , ..., P 1-5 The specific operations include: from P 1-1 (At position 1995m) Perforation operation begins. Nozzle sub 7 is adjusted to the 1995m position. Perforation fluid carrying abrasive is pumped through tubing 4. The viscosity of the perforation fluid is 20 mPa·s, well-compatible with the reservoir. The abrasive used is 40 / 70 quartz sand with a sand ratio of 7%. It is injected into production casing 2 through nozzle sub 7. The flow velocity in the orifice of nozzle sub 7 is 210 m / s. The perforation time for a single cluster is 15 minutes. The fluid is then returned through the annulus of tubing 4 and production casing 2. 1-1 After the perforation operation is completed, pull up the tubing for 4 pairs of P. 1-2 (At position 1985m) The same process and parameters are used to carry out hydraulic sandblasting perforation operations. This process is repeated until all perforation clusters in the first section are completed. Large-diameter, deep-penetrating hydraulic jet channels 10 are established in the near-wellbore reservoir of the first section to effectively remove near-wellbore reservoir contamination and achieve the goal of increasing production.

[0066] S3, the perforated section is sealed with sand inside the pipe.

[0067] S31, lower the working string to P 1-1 Around the nozzle, adjust the working column to offset the nozzle section 7 from the injection hole.

[0068] S32, using oil pipe 4 pump to inject settling fluid. The viscosity of the settling fluid is 5 mPa·s. 12 / 20 mesh filler is added to the settling fluid, resulting in a density of 1.6 g / cm³. 3 The ceramsite has a sand ratio of 50%. The flow velocity of the settling fluid in tubing 4 is greater than the critical sand-carrying velocity in tubing 4, but less than the critical sand-carrying velocity in the annulus between tubing 4 and production casing 2. The settling fluid is injected into production casing 2 through nozzle stub 7 and discharged back through the annulus between tubing 4 and production casing 2. When the ceramsite flows out of nozzle stub 7, it settles due to the decrease in annular velocity, forming an in-tube sand plug in production casing 2, sealing P. 1-1 Slowly raise the working string to P. 1-2 Around the nozzle, the nozzle section 7 is staggered from the injection orifice, and the same process and parameters are used to complete P. 1-2 The blocking, and so on, completes P. 1-3 To P 1-4 The blockade, retaining P 1-5 Do not block it.

[0069] It should be noted that, in order to prevent the tubing from being buried by sand during the sand filling process, the tubing should be moved up and down slightly after the sand-settling fluid exits the nozzle section 7. During the sand filling and sealing operation, it is inevitable that a small amount of ceramic particles will enter the annulus between the production casing 2 and the open hole 1 through the perforation holes. The small amount of ceramic particles will not affect the subsequent gravel filling operation.

[0070] S4, Circumferential gravel backfilling for sand control operation.

[0071] S41, drag the working string, lift the working string, rotate it forward, and then lower it to compress, sealing the packer 6 (Y221 packer) seat to P. 1-4 To P 1-5 In between, the function of the working tubing was changed to that of a sand-filled return tubing.

[0072] S42, injecting gravel-laden filling fluid into the annulus between tubing 4 and production casing 2. The gravel has a density of 1.15 g / cm³. 3 The resin balls have a particle size of 40 / 70, the gravel has a sand ratio of 10%, and the filling fluid contains 7% fiber by mass. The gravel-carrying filling fluid is then processed by P... 1-5 Gravel enters the annulus between production casing 2 and open hole 1. Due to the action of the sand plug inside the casing, the gravel remains in the annulus between production casing 2 and open hole 1. The filling fluid passes through P... 1-1 To P 1-4 The sand plug enters the tubing and flows through the nozzle stub 7 and check valve 8 of the working tubing into the tubing 4, returning to the surface. This creates a gravel-filled layer in the annulus between the production casing 2 and the open hole 1, effectively preventing sand buildup.

[0073] It should be noted that, in order to improve the protection of the reservoir, a filling fluid that is well compatible with the reservoir should be selected, and the bottom hole pressure generated by the injection should be controlled below the formation fracture pressure.

[0074] S43. As gravel accumulates in the annulus of production casing 2 and open hole 1, the filling pressure slowly increases. The sand ratio is appropriately reduced to 5% to continue filling. When the injection pressure reaches the desanding pressure, the injection is stopped. The tubing string is lifted to release the packer 6. Displacement fluid is pumped in using tubing 4 and injected into production casing 2 through nozzle stub 7. The filling fluid in the annulus of tubing 4 and production casing 2 is displaced out of the wellhead, completing the first stage of gravel filling construction.

[0075] S5. Repeat steps S2 to S4 for the second segment, and so on, until the sixth segment is completed. Specifically, taking the nth segment as an example (2≤n≤6), first perform water jet perforation to increase production, such as... Figure 1 As shown, along the direction from point B to point A, we successively obtain P. n-1 P n-2 Pn-3 P n-4 P n-5 , ..., P n-m m≥5; then, the perforated section is sealed with sand inside the pipe. A working string is used to fill the nth section with sand to form a sand plug inside the pipe, so that P n-1 To P n-(m-1) Blocking, P n-m Do not seal; then carry out ring gravel backfilling for sand control, such as Figure 2 and Figure 3 As shown, a gravel-laden filling fluid is injected into the annulus between the working tubing 4 and the production casing 2, and P... n-m Gravel remained in the annulus of production casing 2 and open hole 1, and the filling fluid was passed through P n-1 To P n-(m-1) The sand plug enters the pipe, and then returns to the surface through pipe 4, as shown. Figure 4 and Figure 5 As shown, an in-tube sand plug containing ceramic particles 11 is formed inside the production casing 2, and a gravel packing layer containing fibers 13 and resin balls 12 is formed in the annulus between the production casing 2 and the open hole wellbore 1 and in the hydraulic jet channel 10.

[0076] S6, reverse sand flushing and well cleaning operation.

[0077] S61, lift the working tubing, replace the clear oil tubing 4 and lower the production sleeve 2.

[0078] S62, using the annulus of the bare tubing 4 and production casing 2, inject flushing fluid, alternately injecting low-viscosity flushing fluid with a viscosity of 10 mPa·s and high-viscosity flushing fluid with a viscosity of 100 mPa·s, and backflow from the bare tubing 4 until the sand plug inside the tubing from point A to point B is flushed, and the wellbore is cleared before well production begins.

[0079] Example 2 This embodiment provides a segmented unclogging and production enhancement method for horizontal well casing uncemented completion, along with filling and sand control. Taking a loose sandstone reservoir as the research object, a horizontal well was completed using 5-1 / 2″ N80 production casing uncemented completion at a depth of 2000m. The horizontal section of the well was 300m long. A casing hanger was used to suspend the production casing at the wellhead within the open hole. During drilling, the drilling fluid caused some damage to the near-wellbore zone of the reservoir, resulting in a high skin coefficient, necessitating unclogging to increase production capacity. Furthermore, due to the loose reservoir and low cementation strength, severe sand production occurred during production, requiring sand control considerations during completion. To simultaneously achieve the requirements of unclogging production and sand control, the method described in this embodiment includes the following steps: S1, divide the horizontal section of the production casing into well sections.

[0080] Based on the heterogeneous characteristics of horizontal wells, the section from the end point B to the target point A is divided into six segments: segment 1, segment 2, ..., segment 6. The segments are: segment 1 1950-2000m, segment 2 1900-1950m, segment 3 1850-1900m, segment 4 1800-1850m, segment 5 1750-1800m, and segment 6 1700-1750m.

[0081] S2, water jetting and perforation for increased production.

[0082] Along the direction from point B to point A, assemble the tubing guide shoe, check valve, nozzle sub, packer, safety joint, and tubing in sequence to obtain the working tubing string.

[0083] S21, lower the working tubing into the first section of the production casing.

[0084] S22, based on the engineering geological characteristics of the horizontal well reservoir, the spacing of each cluster of perforations is set to 10m. Starting from the end of the first section closest to point B, five clusters of hydraulic sandblasting perforations are performed on the first section to penetrate the production casing, resulting in the first cluster of perforations, the second cluster of perforations, ..., the fifth cluster of perforations, denoted as P. 1-1 P 1-2 , ..., P 1-5 The specific operations include: from P 1-1 (At position 1995m) Perforation operation begins. The nozzle sub is adjusted to the 1995m position. Perforation fluid carrying abrasive is pumped in through the tubing. The viscosity of the perforation fluid is 20 mPa·s, which is well-compatible with the reservoir. The abrasive used is 40 / 70 quartz sand with a sand ratio of 6%. It is injected into the production casing through the nozzle sub. The flow velocity in the nozzle sub orifice is 190 m / s. The perforation time for a single cluster is 12 min. The fluid is then returned through the annulus between the tubing and the production casing. P 1-1 After the perforation operation is completed, pull up the tubing to P 1-2 (At the 1985m location) The same process and parameters are used to carry out hydraulic sandblasting perforation operations. This process is repeated until all perforation clusters in the first section are completed. Large-diameter, deep-penetrating hydraulic jet channels are established in the near-wellbore reservoir of the first section to effectively remove near-wellbore reservoir contamination and achieve the goal of increasing production.

[0085] S3, the perforated section is sealed with sand inside the pipe.

[0086] S31, lower the working string to P 1-1 Around the nozzle, adjust the working column to offset the nozzle section from the injection hole.

[0087] S32, using an oil pipe pump to inject settling fluid, the viscosity of which is 5 mPa·s, and 12 / 20 mesh additive with a density of 1.8 g / cm³ is added to the settling fluid. 3The ceramsite has a sand ratio of 50%. The flow velocity of the sedimentation fluid in the tubing is greater than the critical sand-carrying velocity in the tubing, but less than the critical sand-carrying velocity in the annulus between the tubing and the production casing. The sedimentation fluid is injected into the production casing through a nozzle stub and then discharged back through the annulus between the tubing and the production casing. When the ceramsite flows out of the nozzle stub, it settles due to the reduced annular velocity, forming a sand plug inside the production casing and sealing P. 1-1 Slowly raise the working string to P. 1-2 Around the perimeter, the nozzle short section is staggered from the injection orifice, and the same process and parameters are used to complete P. 1-2 The blocking, and so on, completes P. 1-3 To P 1-4 The blockade, retaining P 1-5 Do not block it.

[0088] It should be noted that, in order to prevent the tubing from being buried by sand during the sand filling process, the tubing should be moved up and down slightly after the sand-settling fluid exits the nozzle section. During the sand filling and sealing operation, it is inevitable that a small amount of ceramic particles will enter the annulus between the production casing and the open hole through the perforation holes. This small amount of ceramic particles will not affect the subsequent gravel filling operation.

[0089] S4, Circumferential gravel backfilling for sand control operation.

[0090] S41, drag the working string, lift the working string, rotate it forward, and then lower it for compression, sealing the packer (Y221 packer) seat at P. 1-4 To P 1-5 In between, the function of the working tubing was changed to that of a sand-filled return tubing.

[0091] S42, using the annulus between the tubing and the production casing, injects a packing fluid carrying gravel. The gravel has a density of 1.15 g / cm³. 3 The resin balls have a particle size of 40 / 70, the gravel has a sand ratio of 15%, and the filling fluid contains 10% fiber by mass. The gravel-carrying filling fluid is then processed by P... 1-5 Gravel enters the annulus between the production casing and the open hole. Due to the action of the sand plug inside the casing, the gravel remains in the annulus between the production casing and the open hole. The filling fluid passes through P... 1-1 To P 1-4 Sand enters the tubing through the nozzle stub and check valve of the working tubing and returns to the surface. This creates a gravel-filled annulus between the production casing and the open hole, effectively controlling sand production.

[0092] It should be noted that, in order to improve the protection of the reservoir, a filling fluid that is well compatible with the reservoir should be selected, and the bottom hole pressure generated by the injection should be controlled below the formation fracture pressure.

[0093] S43. As gravel accumulates in the annulus of the production casing and open hole, the filling pressure slowly increases. The sand ratio is appropriately reduced to 5% and filling continues. When the injection pressure reaches the desanding pressure, injection is stopped. The tubing string is lifted to release the packer, and displacement fluid is injected using the tubing pump. The fluid is then injected into the production casing through the nozzle sub, displacing the filling fluid in the annulus of the tubing and production casing out of the wellhead, thus completing the first stage of gravel filling.

[0094] S5. Repeat steps S2 to S4 for the second segment, and so on, until the sixth segment is completed. S6, reverse sand flushing and well cleaning operation.

[0095] S61, lift the work string, replace the bare oil pipe and lower it into the production casing.

[0096] S62 utilizes the annulus of the tubing and production casing to inject flushing fluid, alternately injecting low-viscosity flushing fluid with a viscosity of 10 mPa·s and high-viscosity flushing fluid with a viscosity of 100 mPa·s, and then backflowing it from the tubing until the sand plug inside the tubing from point A to point B is flushed out, and the wellbore is cleared before well production begins.

[0097] Example 3 This embodiment provides a segmented unclogging and production enhancement method for horizontal well casing uncemented completion, along with filling and sand control. Taking a loose sandstone reservoir as the research object, a horizontal well was completed using 5-1 / 2″ N80 production casing uncemented completion at a depth of 2000m. The horizontal section of the well was 300m long. A casing hanger was used to suspend the production casing at the wellhead within the open hole. During drilling, the drilling fluid caused some damage to the near-wellbore zone of the reservoir, resulting in a high skin coefficient, necessitating unclogging to increase production capacity. Furthermore, due to the loose reservoir and low cementation strength, severe sand production occurred during production, requiring sand control considerations during completion. To simultaneously achieve the requirements of unclogging production and sand control, the method described in this embodiment includes the following steps: S1, divide the horizontal section of the production casing into well sections.

[0098] Based on the heterogeneous characteristics of horizontal wells, the section from the end point B to the target point A is divided into six segments: segment 1, segment 2, ..., segment 6. The segments are: segment 1 1950-2000m, segment 2 1900-1950m, segment 3 1850-1900m, segment 4 1800-1850m, segment 5 1750-1800m, and segment 6 1700-1750m.

[0099] S2, water jetting and perforation for increased production.

[0100] Along the direction from point B to point A, assemble the tubing guide shoe, check valve, nozzle sub, packer, safety joint, and tubing in sequence to obtain the working tubing string.

[0101] S21, lower the working tubing into the first section of the production casing.

[0102] S22, based on the engineering geological characteristics of the horizontal well reservoir, the spacing of each cluster of perforations is set to 10m. Starting from the end of the first section closest to point B, five clusters of hydraulic sandblasting perforations are performed on the first section to penetrate the production casing, resulting in the first cluster of perforations, the second cluster of perforations, ..., the fifth cluster of perforations, denoted as P. 1-1 P 1-2 , ..., P 1-5 The specific operations include: from P 1-1 (At position 1995m) Perforation operation begins. The nozzle sub is adjusted to the 1995m position. Perforation fluid carrying abrasive is pumped in through the tubing. The viscosity of the perforation fluid is 20 mPa·s, which is well-compatible with the reservoir. The abrasive used is 40 / 70 quartz sand with a sand ratio of 5%. It is injected into the production casing through the nozzle sub. The flow velocity in the nozzle sub orifice is 180 m / s. The perforation time for a single cluster is 10 min. The fluid is then returned through the annulus between the tubing and the production casing. P 1-1 After the perforation operation is completed, pull up the tubing to P 1-2 (At the 1985m location) The same process and parameters are used to carry out hydraulic sandblasting perforation operations. This process is repeated until all perforation clusters in the first section are completed. Large-diameter, deep-penetrating hydraulic jet channels are established in the near-wellbore reservoir of the first section to effectively remove near-wellbore reservoir contamination and achieve the goal of increasing production.

[0103] S3, the perforated section is sealed with sand inside the pipe.

[0104] S31, lower the working string to P 1-1 Around the nozzle, adjust the working column to offset the nozzle section from the injection hole.

[0105] S32, using an oil pipe pump to inject settling fluid, the viscosity of which is 5 mPa·s, and 12 / 20 mesh additive with a density of 1.5 g / cm³ is added to the settling fluid. 3 The ceramsite has a sand ratio of 50%. The flow velocity of the sedimentation fluid in the tubing is greater than the critical sand-carrying velocity in the tubing, but less than the critical sand-carrying velocity in the annulus between the tubing and the production casing. The sedimentation fluid is injected into the production casing through a nozzle stub and then discharged back through the annulus between the tubing and the production casing. When the ceramsite flows out of the nozzle stub, it settles due to the reduced annular velocity, forming a sand plug inside the production casing and sealing P. 1-1 Slowly raise the working string to P. 1-2 Around the perimeter, the nozzle short section is staggered from the injection orifice, and the same process and parameters are used to complete P. 1-2 The blocking, and so on, completes P. 1-3 To P 1-4 The blockade, retaining P 1-5 Do not block it.

[0106] It should be noted that, in order to prevent the tubing from being buried by sand during the sand filling process, the tubing should be moved up and down slightly after the sand-settling fluid exits the nozzle section. During the sand filling and sealing operation, it is inevitable that a small amount of ceramic particles will enter the annulus between the production casing and the open hole through the perforation holes. This small amount of ceramic particles will not affect the subsequent gravel filling operation.

[0107] S4, Circumferential gravel backfilling for sand control operation.

[0108] S41, drag the working string, lift the working string, rotate it forward, and then lower it for compression, sealing the packer (Y221 packer) seat at P. 1-4 To P 1-5 In between, the function of the working tubing was changed to that of a sand-filled return tubing.

[0109] S42, using the annulus between the tubing and the production casing, injects a packing fluid carrying gravel. The gravel has a density of 1.00 g / cm³. 3 The resin balls have a particle size of 40 / 70, the gravel has a sand ratio of 5%, and the filling fluid contains 5% fiber by mass. The gravel-carrying filling fluid is then processed by P... 1-5 Gravel enters the annulus between the production casing and the open hole. Due to the action of the sand plug inside the casing, the gravel remains in the annulus between the production casing and the open hole. The filling fluid passes through P... 1-1 To P 1-4 Sand enters the tubing through the nozzle stub and check valve of the working tubing and returns to the surface. This creates a gravel-filled annulus between the production casing and the open hole, effectively controlling sand production.

[0110] It should be noted that, in order to improve the protection of the reservoir, a filling fluid that is well compatible with the reservoir should be selected, and the bottom hole pressure generated by the injection should be controlled below the formation fracture pressure.

[0111] S43. As gravel accumulates in the annulus of the production casing and open hole, the filling pressure slowly increases. The sand ratio is appropriately reduced to 5% and filling continues. When the injection pressure reaches the desanding pressure, injection is stopped. The tubing string is lifted to release the packer, and displacement fluid is injected using the tubing pump. The fluid is then injected into the production casing through the nozzle sub, displacing the filling fluid in the annulus of the tubing and production casing out of the wellhead, thus completing the first stage of gravel filling.

[0112] S5. Repeat steps S2 to S4 for the second segment, and so on, until the sixth segment is completed. S6, reverse sand flushing and well cleaning operation.

[0113] S61, lift the work string, replace the bare oil pipe and lower it into the production casing.

[0114] S62 utilizes the annulus of the tubing and production casing to inject flushing fluid, alternately injecting low-viscosity flushing fluid with a viscosity of 10 mPa·s and high-viscosity flushing fluid with a viscosity of 100 mPa·s, and then backflowing it from the tubing until the sand plug inside the tubing from point A to point B is flushed out, and the wellbore is cleared before well production begins.

[0115] In summary, the method provided by this invention combines hydraulic perforation for unblocking and production enhancement with gravel packing for sand control. It utilizes a work string to perform segmented operations on horizontal wells, and can achieve integrated production enhancement and sand control operations with just one set of work string, significantly improving the efficiency of construction operations.

[0116] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for staged unclogging and sand control in horizontal well casing uncemented completion, characterized in that, The method includes the following steps: S1, divide the horizontal section of the production casing into well sections; The horizontal segment from the end point B to the target entry point A is divided into segments 1, 2, ..., N, where N ≥ 2; S2, water jet perforation for increased production; A multi-cluster hydraulic sandblasting perforation operation is carried out on the nth production casing using a working tubing, where 1≤n<N; along the direction from point B to point A, the first cluster of perforations, the second cluster of perforations, ..., the mth cluster of perforations are obtained sequentially, where m≥2; S3, filling the pipe with sand to seal the perforated section; The working tubing is used to fill the nth section with sand to form a sand plug inside the tubing, thus sealing the perforation holes of the first to the (m-1)th clusters, while leaving the perforation holes of the mth cluster unsealed. S4, Circumferential gravel backfilling for sand control; The filling fluid carrying gravel is injected into the annulus between the tubing and the production casing of the working tubing string. The filling fluid enters the annulus between the production casing and the open hole through the perforation holes of the nth section and the mth cluster, where gravel remains. The filling fluid enters the sand plug inside the tubing through the perforation holes of the nth section from the 1st cluster to the m-1st cluster, and then returns to the surface through the tubing. S5. Repeat steps S2 to S4 for the (n+1)th segment, and so on, until the Nth segment is completed. S6, reverse sand flushing and well cleaning operation.

2. The method according to claim 1, characterized in that, Before dividing the horizontal section of the production casing into well sections, the target well is completed using a completion string; Preferably, the completion string includes a production casing and a casing hanger; Preferably, the working string includes a tubing guide shoe, a check valve, a nozzle sub, a packer, a safety joint, and tubing arranged sequentially along the direction from point B to point A.

3. The method according to claim 2, characterized in that, Step S2 specifically includes the following steps: S21, lower the working tubing into the nth segment of the production casing; S22, starting from the end of the nth segment near point B, performs multi-cluster hydraulic sandblasting perforation to penetrate the production casing and connect the reservoir.

4. The method according to claim 3, characterized in that, The multi-cluster hydraulic jet perforation operation includes: pumping perforation fluid carrying abrasive material through tubing, injecting it into the production casing through a nozzle sub, performing hydraulic jet perforation through annular backflow between the tubing and the production casing, establishing a hydraulic jet channel in the near-wellbore reservoir, and performing m hydraulic jet perforation operations on the nth section by raising the tubing. Each hydraulic jet perforation operation forms a cluster of perforations, where the mth cluster of perforations in the nth section is denoted as P. n-m ; Preferably, the viscosity of the perforating fluid is 20~30 mPa·s; Preferably, the abrasive comprises silica sand; Preferably, the abrasive has a sand ratio of 5-7%; Preferably, the orifice velocity of the nozzle section is 180~210m / s; Preferably, the single-cluster perforation time for the water jet perforation operation is 10-15 minutes; Preferably, the spacing between adjacent perforations is 8-10m.

5. The method according to any one of claims 2 to 4, characterized in that, Step S3 specifically includes the following steps: S31, lower the working string into the first cluster perforation hole of the nth segment, i.e., P. n-1 Around, and make the nozzle short section of the working tube stagger the injection hole; S32, using a tubing pump to inject sedimentation fluid, which is then injected into the production casing through a nozzle short section. The fluid is flushed back through the annulus between the tubing and the production casing, forming an internal sand plug within the production casing. The work string is then dragged to seal the perforations from the first cluster to the (m-1)th cluster in the nth segment, i.e., P. n-1 To P n-(m-1) And the mth cluster aperture is P n-m Do not block it.

6. The method according to claim 5, characterized in that, The settling liquid includes ceramsite; Preferably, the density of the ceramsite is 1.5~1.8 g / cm³. 3 ; Preferably, the sand ratio of the ceramsite is ≥50%.

7. The method according to any one of claims 2 to 6, characterized in that, Step S4 specifically includes the following steps: S41, seal the packer seat of the working string to the perforation holes of the nth segment from the mth cluster to the (m-1)th cluster, i.e., P. n-m To P n-(m-1) between; S42, filler fluid carrying gravel is injected into the annulus between the tubing and the production casing. The filler fluid carrying gravel passes through the m-th perforation hole in the nth segment, i.e., P. n-m The gravel enters the annulus between the production casing and the open hole, thereby performing gravel packing operations in the annulus of the production casing and the open hole, as well as in the hydraulic jet channel. Under the action of the sand plug inside the casing, the gravel remains in the annulus of the production casing and the open hole. The packing fluid passes through the perforations from the first cluster to the (m-1)th cluster in the nth section, i.e., P... n-1 To P n-(m-1) The sand plug enters the pipe and passes through the nozzle stub and check valve of the working tubing into the tubing, then returns to the surface; S43. When the injection pressure reaches the desanding pressure, stop the injection, release the packer, use the tubing pump to inject displacement fluid, and inject it into the production casing through the nozzle sub. Displace the filling fluid in the annulus of the tubing and production casing out of the wellhead, thus completing the construction.

8. The method according to claim 7, characterized in that, The gravel includes resin balls; Preferably, the density of the gravel is 1.00~1.10 g / cm³. 3 ; Preferably, the gravel has a sand ratio of 5-15%; Preferably, the filling fluid is infused with fibers; Preferably, the fiber content in the filling liquid is 5-10% by mass.

9. The method according to any one of claims 1 to 8, characterized in that, Step S6 specifically includes the following steps: S61, replace the working tubing with a clear oil tubing and lower it into the production casing; S62 utilizes the annulus of the bare tubing and production casing to inject flushing fluid, which is then returned from the bare tubing until the sand plug inside the tubing from point A to point B is flushed out, clearing the wellbore before well production begins.

10. The method according to claim 9, characterized in that, The annulus of the clear oil pipe and the production casing is alternately injected with low-viscosity sand-washing fluid and high-viscosity sand-washing fluid. Preferably, the viscosity of the low-viscosity sand-washing fluid is 10~20 mPa·s; Preferably, the viscosity of the high-viscosity sand flushing fluid is 50~100 mPa·s.

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