CN112443306B - Pressure-control fracturing method for increasing fracture complexity of deep shale gas well - Google Patents
Pressure-control fracturing method for increasing fracture complexity of deep shale gas well Download PDFInfo
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- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/25—Methods for stimulating production
- E21B43/26—Methods for stimulating production by forming crevices or fractures
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/25—Methods for stimulating production
- E21B43/26—Methods for stimulating production by forming crevices or fractures
- E21B43/267—Methods for stimulating production by forming crevices or fractures reinforcing fractures by propping
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Abstract
The invention discloses a pressure-controlled fracturing method for increasing fracture complexity of a deep shale gas well, which comprises the following steps of: 1) Evaluating key shale parameters and optimizing fracturing construction parameters; 2) Carrying out perforation operation; 3) Carrying out acid treatment; 4) Adopting high-viscosity glue solution to make a main seam; 5) Injecting high-viscosity slick water carrying 80-120 meshes of propping agent; 6) Injecting high-viscosity slick water carrying 40-70 mesh proppant; 7) Injecting high-viscosity glue solution; 8) Injecting an acidic slick water system; 9) Repeating the step 6 to the step 8 for more than two times; 10 Injecting high-viscosity glue solution carrying 40-70 meshes of propping agent; 11 Adopting a displacement liquid to carry out displacement operation, and then putting a bridge plug in; 12 Repeating the steps 2-11 until all the sections are constructed, and finally drilling and plugging, returning, testing and solving the production after pressing. The invention realizes the high-efficiency transformation of deep shale gas by using the acid slickwater to replace the high-viscosity liquid and matching with the variable-displacement fracturing process.
Description
Technical Field
The invention relates to the field of oil field development, in particular to a shale gas well staged multi-cluster fracturing technology, specifically relates to a hydraulic fracturing method suitable for a deep shale gas well, and particularly relates to a pressure-controlled fracturing method for increasing the complexity of cracks of the deep shale gas well.
Background
5363 the deep shale gas resource of blocks such as Jiao Danba, weiyuan, dingshan and the like is abundant and has large gas containing area, statistics shows that 3500m deep shale gas resource accounts for more than 65% of the total resource, wherein 3500m deep shale gas resource of Sichuan basin is up to 4612 × 10 8 m 3 Therefore, the successful development of deep shale gas resources has important significance for further mining and increasing potential storage in China.
Development practices show that the deep shale gas well has low porosity and low permeability, and efficient development can be realized by establishing a high-flow-guide fracture network in the shale gas reservoir. On one hand, however, with the increase of the depth, the shale under the deep buried reservoir has stronger plasticity, large horizontal main stress difference, difficult opening of natural cracks such as high-angle seams, bedding seams and the like, and larger difficulty in forming a multi-scale crack network; on the other hand, the deep shale gas well has narrow fracturing cracks and limited sand adding strength, and sand is added at high strength in a mode of improving the viscosity of slickwater, properly increasing the proportion of glue solution and the like on site, but the high-viscosity fracturing fluid is not beneficial to forming a complex crack network.
Chinese patent CN107476790A discloses a pressure-limiting and displacement-unlimited fracturing method for improving the modification volume of a shale gas fracture, which comprises the following steps: (1) Evaluating a reservoir before fracturing and evaluating the reservoir in real time in the early stage of fracturing construction; (2) Carrying out a layering small-scale test fracturing test on a vertical well pilot hole; (3) performing simulation analysis by using software MEYER; (4) Normal fracturing construction is carried out, and one or two times of instantaneous pump stopping are carried out in the construction process; (5) reversely deducing the expected pressure of the wellhead construction from the bottom hole pressure; (6) Increasing the displacement as long as the construction pressure of the well head is lower than the expected pressure in the step (5), so that the construction pressure of the well head is close to the expected value; (7) And if the wellhead construction pressure after the displacement is increased does not reach the expected pressure, the construction sand-liquid ratio is increased. Various problems caused by using a limited displacement method can be improved, so that the actual post-compression modification volume of the shale reservoir and the complexity of artificial fractures are improved.
The method for improving the deep shale gas crack complexity index in the Chinese patent CN 106567702A. According to the method, when the deep shale gas well is fractured, the fracturing fluid selection and injection mode, the proppant selection, the cluster perforation number and other technological methods are optimally designed and controlled, so that the artificial main fractures are opened as much as possible in the extending process and communicate with natural fractures in the stratum; the single fracture is extended longer and expanded more widely, and finally the purpose of improving the complexity of the fracturing fracture of the shale gas well to the maximum extent is achieved. However, natural cracks filled with carbonate minerals are distributed in the modification range of the artificial main cracks, and a certain included angle exists between the fracturing main cracks and the natural cracks, so that the applicability is low.
Chinese patent CN106382111a proposes a method for increasing complexity of shale gas fracturing fracture, comprising: the brittleness index of the stratum is improved, and the viscosity of the fracturing fluid is reduced; controlling the sanding time according to the seam length and the seam width extension range of the natural fracture; and increasing one or more of the fracturing fluid viscosity, fluid volume, displacement volume, and construction sand-fluid ratio to induce multiple diversion of the primary fracture. However, the temporary plugging agent in the crack is adopted to force the crack to turn, and the temporary plugging times and the fracturing scale have certain limitations under a narrow construction pressure window.
Chinese patent CN109113703A discloses a deep shale gas 'V' -shaped pressure curve fracturing method. The method comprises the following steps: (1) evaluating key reservoir parameters; (2) optimizing fracture parameters and fracturing construction parameters; (3) determining a perforation position and performing perforation operation; (4) acid pretreatment; (5) variable-displacement low-viscosity slick water seam construction; (6) constructing low-viscosity slickwater by adding powder ceramics with different sand-to-liquid ratios; (7) Adding medium-grain-size propping agents with different sand-to-liquid ratios into medium-stick-slip slick water for construction; (8) carrying a propping agent with high-viscosity glue liquid and large particle size; and (9) performing replacement operation. However, there is a limit to its complexity in increasing fractures under high levels of differential primary stress.
Chinese patent CN108952668a provides a fracturing method for normal pressure shale gas reservoir, which comprises the following steps: step one, obtaining reservoir evaluation parameters; determining fracturing construction parameters, wherein the parameters comprise viscosity, discharge capacity and consumption of a fracturing fluid, and particle size and consumption of a propping agent; step three, fracturing construction; and in the third step, a spiral section plug type mixed particle size sand adding mode is adopted to perform section-by-section fracturing construction on the reservoir. But it is mainly suitable for normal pressure shale gas, but not deep shale gas.
Therefore, the difficulty of establishing a complex fracture network in a deep shale gas reservoir by adopting a conventional method is very high. Although multi-scale reconstruction under the condition of high horizontal stress difference can be realized in the medium-deep well through in-seam temporary plugging steering fracturing, the temporary plugging agent has longer self-degradation time, the temporary plugging times during fracturing are limited, and the pressure rise range is high after the temporary plugging is successful, so that the construction pressure window is further reduced under the conditions of deep burial depth and high closing pressure, and the fracturing construction difficulty is increased. Therefore, a deep shale gas well pressure control fracturing method capable of increasing fracture complexity is needed.
Disclosure of Invention
The invention provides a pressure control fracturing method of a deep shale gas well, which solves the problems that the construction pressure window is narrow and the complexity of cracks is difficult to improve when the existing deep shale gas well is fractured, namely, the net pressure in the cracks is improved by adjusting the discharge capacity of glue solution and isolation solution, so that natural cracks are opened, and the rising speed of ground pump pressure is controlled under the narrow construction pressure window; then pumping acid slick water, further extending and communicating natural fractures through viscosity fingering and acid dissolution, and improving fracture complexity; meanwhile, the long-term flow conductivity of the reconstructed volume is further enhanced by using the carried small-particle-size proppant. Therefore, the invention solves the problems of small effective modification volume, low crack complexity and narrow construction pressure window of the deep shale gas well by replacing high-viscosity liquid with the acidic slickwater and matching with the variable displacement fracturing process, and realizes the efficient modification of the deep shale gas.
The invention aims to provide a pressure-control fracturing method for increasing fracture complexity of a deep shale gas well, which comprises the following steps:
step 1, evaluating key shale parameters and optimizing fracturing construction parameters.
In step 1, parameters are evaluated and optimized using means disclosed in the prior art, for example, key shale parameters including formation of interest, geology, lithology, mineral composition, physical properties, rock mechanics, tri-directional stress characteristics, natural fracture characteristics, etc., are evaluated using methods including comprehensive application of seismic, logging, testing, and indoor core analysis.
And 2, performing perforation operation.
In a preferred embodiment, in step 2, a bridge plug perforation combination method is used for perforation.
In a further preferred embodiment, the first section is run into the gun using coiled tubing without a bridge plug, and the other sections are run into the bridge plug and gun using pumping.
In a further preferred embodiment, after the bridge plug reaches a preset position, the bridge plug is set and released, then the perforating gun is lifted up step by step, and after all perforating is finished, the perforating gun tube string is lifted up.
And 3, carrying out acid treatment.
In a preferred embodiment, in step 3, the amount of acid is from 10 to 20m 3 The discharge capacity of the acid injection is 1 to 1.5m 3 The discharge amount of the acid substitute is generally 4-6 m 3 /min。
In a further preferred embodiment, after the acid reaches the injection hole position, the displacement of the acid is reduced to the displacement of the acid injection, so that the contact time of the acid rock and the acidification effect are increased.
In a further preferred embodiment, the acid is allowed to enter the first cluster of holes by 8 to 10m 3 Then, the displacement of the acid substitute is increased to 6 to 8m 3 Min to ensure that the remaining acid enters other perforation clusters.
In a preferred embodiment, in step 3, the viscosity of the acid is 5 to 10cp.
The method mainly considers that the stratum temperature of the deep shale gas reservoir is high, and the viscosity of the acid liquor is increased to 5-10 cp in order to avoid the over-high release speed of hydrogen ions.
And 4, manufacturing a main seam by using high-viscosity glue solution.
In a preferred embodiment, in step 4, the viscosity of the high-viscosity glue solution is 60 to 80cp.
In a further preferred embodiment, in step 4, the liquid volume of the high-viscosity glue solution is 1 to 3 times of the well bore volume, and the discharge capacity is the optimized discharge capacity of step 1.
And step 5, injecting high-viscosity slick water carrying 80-120 meshes of propping agent.
Wherein, in the step 5, the viscosity of the high-viscosity slickwater is 9-12 cp.
In a preferred embodiment, in step 5, the sand is added in a slug mode, and the sand-liquid ratio is 1-2-3-4-5%.
In a further preferred embodiment, the amount of each sand carrying fluid relative to the lower sand carrying fluid is 60 to 90% of the wellbore volume, and the amount of spacer fluid is 1 to 1.1 times the amount of the sand carrying fluid.
And 6, injecting high-viscosity slick water carrying 40-70 meshes of propping agent.
Wherein, in step 6, the viscosity of the high-viscosity slickwater is 9-12 cp.
In a preferred embodiment, in step 6, the sand-to-fluid ratio is 3 to 4 to 5 to 6%, and the liquid amount of the sand-carrying liquid at each sand-to-fluid ratio is 70 to 100% of the volume of the wellbore.
In a further preferred embodiment, the first 3 sand-liquid ratios are obtained by adding sand in a slug mode, and the liquid amount of the sand-carrying liquid in each segment is 1-1.5 times of the liquid amount of the isolation liquid; and finally, continuously adding sand in the sand-liquid ratio of 1.
And 7, injecting high-viscosity glue solution.
Wherein, in the step 7, the viscosity of the high-viscosity glue solution is 60-80 cp.
In a preferred embodiment, in step 7, the discharge capacity of the high-viscosity glue solution is 14-18 m 3 And/min, the liquid volume of the high-viscosity glue solution is 1-2 times of the volume of the shaft.
The method is characterized in that the net pressure in the crack is improved by adjusting the discharge capacity of the glue solution, so that the natural crack is opened, the rising speed of the ground pump pressure is controlled under a narrow construction pressure window, and the glue solution amount or the construction discharge capacity can be properly increased if the ground pump pressure is not remarkably increased (the amplification is less than 2MPa/min or has no rising trend).
And 8, injecting an acidic slickwater system.
Wherein the viscosity of the acid slickwater is 1-5 cp.
In a preferred embodiment, step 8 comprises the following sub-steps:
step 8.1, injecting acidic slick water;
in step 8.1, the amount of acidic slickwater injected is 50-60% of the wellbore volume.
Wherein the main purpose of step 8.1 is to percolate to the fracture walls and ends by viscosity fingering to prevent subsequent 80-120 mesh proppant from being heavily blended with cement to settle in the primary fracture.
Step 8.2, injecting acidic slick water carrying 80-120 meshes of propping agent;
in step 8.2, the sand-liquid ratio is 4-8%, and the liquid volume of the acidic slickwater is 1-2 times of the volume of the shaft.
The main purpose of step 8.2 is to reduce the difficulty of opening the natural fracture by utilizing the acid corrosion property of the fracture to react with the carbonic acid filler in the natural fracture, so that the branch fracture extension is promoted by matching with the low viscosity characteristic of the fracture. The proppant is 80-120 meshes, and is mainly used for improving the long-term flow conductivity of the branch joints and avoiding the influence of the filtration loss of the branch joints on the subsequent fracturing construction.
And 8.3, injecting the acidic slick water containing the gel breaker.
In step 8.3, the amount of acidic slick water containing the gel breaker is 1 to 2 times the volume of the wellbore.
And 8.3, further breaking the gel by using the acidity of the gel breaker and the carried gel breaker to reduce the subsequent construction pressure, and replacing the silt to the deep part of the branch joint to improve the long-term flow conductivity of the branch joint.
In actual construction, in step 8, if the ground pressure increases too fast (the ground pressure increases more than 2 MPa/min), the pressure is appliedThe working pressure window is too small, and the discharge capacity can be properly reduced by 2-6 m 3 And/min, increasing the dosage of the gel breaker in the acidic slick water (by 0.5-2 times), and properly increasing the amount of the acidic slick water (by 20-50%).
And 9, repeating the step 6 to the step 8 for more than two times.
In a preferred embodiment, when step 6 is repeated for the first time, the sand adding mode is a slug sand adding mode, the sand-liquid ratio is 6-7-8-9%, the liquid amount of the sand carrying liquid under each sand-liquid ratio is 70-100% of the well bore volume, and the liquid amount of the displacing liquid corresponding to the first three sand-liquid ratios is 1-1.5 times of the corresponding liquid amount of the sand carrying liquid.
In a further preferred embodiment, when step 6 is repeated for the second time, the sand adding mode is a slug adding mode, the sand-liquid ratio is 9-10-11%, the liquid amount of the sand carrying liquid under each sand-liquid ratio is 70-100% of the well bore volume, and the liquid amount of the displacement liquid corresponding to the first three sand-liquid ratios is 1-1.5 times of the corresponding liquid amount of the sand carrying liquid.
In a preferred embodiment, when step 7 is repeated for the first time, the discharge capacity of the high-viscosity glue solution is 14-18 m 3 And/min, the liquid amount of the injected high-viscosity glue solution is 1-2 times of the volume of the shaft.
In a further preferred embodiment, when step 7 is repeated for the second time, the discharge capacity of the high-viscosity glue solution is 14-18 m 3 And/min, the liquid amount of the injected high-viscosity glue solution is 1-2 times of the volume of the shaft.
And (4) when the high-viscosity glue solution is injected in the step (7) repeatedly, the discharge capacity is increased, and the liquid amount of the high-viscosity glue solution is gradually increased. The objective is to further increase the net pressure to open the distal natural fracture. If the pressure increase of the ground pump exceeds 2MPa/min, the liquid cement amount or construction discharge capacity can be properly increased.
In a preferred embodiment, in the first iteration of step 8, the grit ratio used in step 8.2 is between 6 and 10%, the remaining conditions remaining unchanged.
In a further preferred embodiment, when step 8 is repeated a second time, the sand to liquid ratio employed in step 8.2 is 8 to 12%, the remaining conditions being unchanged.
And step 10, injecting high-viscosity glue solution carrying 40-70 meshes of propping agent.
In a preferred embodiment, in step 10, the sand-to-liquid ratio is 10 to 11 to 12 to 13%.
Wherein, the former two sand-liquid ratios adopt slug type sand adding, the 1 st sand-liquid ratio is the 1 st slug, the sand-carrying liquid amount is 80-100% of the shaft volume, and the displacement liquid amount is equal to the shaft volume; the 2 nd sand-liquid ratio is the 2 nd slug, the sand-carrying liquid amount is 70-90% of the volume of the shaft, and the displacement liquid amount is equal to the volume of the shaft; and continuously adding sand into the last four sand-liquid ratios, wherein the sand-carrying liquid amount corresponding to each sand-liquid ratio is 20-50% of the volume of the shaft.
Wherein the viscosity of the high-viscosity glue solution is 60-80 cp.
And 11, adopting the displacement liquid to perform displacement operation, and then putting the bridge plug into the well.
In a preferred embodiment, in step 11, the displacement fluid has a volume of 105 to 110% of the volume of the wellbore in the current interval.
In a further preferred embodiment, the first 30-50% of the displacing liquid is high-viscosity glue liquid with the viscosity of 60-80 cp, and the rest is high-viscosity slippery water with the viscosity of 9-12 cp.
The high-viscosity glue solution is mainly used for cleaning settled sand in the horizontal shaft and providing guarantee for subsequent bridge plug setting and seat sealing.
And 12, repeating the steps 2-11 until all sections are constructed, and finally drilling and plugging after pressing, flowback, testing and solving the production.
Compared with the prior art, the invention has the following beneficial effects:
(1) The invention provides a 'temporary plugging steering' fracturing method without using a temporary plugging agent, wherein the net pressure rise amplitude is controlled in real time by adjusting the discharge capacity of a high-viscosity glue solution;
(2) The subsequent injected acidic slickwater and the carried gel breaker are utilized to timely 'break gel and remove blockage', so that the construction pressure of the deep shale gas well is controlled, and the construction efficiency of multi-scale seam network reconstruction under a narrow construction pressure window is improved;
(3) According to the invention, natural fractures such as bedding, high-angle seams and the like are fully opened by utilizing high net pressure generated when high-viscosity glue solution flows in narrow fractures, the branch seams are further fully extended by virtue of the low viscosity and the acid corrosion of low-viscosity acid slickwater, and the carried silt is used for carrying out saturated filling on the branch seams, so that the complexity of a fracture network is increased, the effective modification volume is increased, and the modification efficiency of a deep shale gas well reservoir is finally improved.
Drawings
Fig. 1 shows a schematic flow diagram of the method according to the invention.
In FIG. 1, 80/120 mesh is said "80-120 mesh", and 40/70 mesh is said "40-70 mesh".
Detailed Description
While the present invention will be described in detail with reference to the following examples, it should be understood that the following examples are illustrative of the present invention and are not to be construed as limiting the scope of the present invention.
The materials of the embodiments of the invention are all available on the market.
Example 1
The D1 shale gas well is located in the southwest Sichuan area, and is 4231m vertical in depth, 6062m sounding in depth and 1504m long in horizontal section. The well has larger buried depth and high construction pressure, and the reservoir stratum is reformed by adopting the pressure-controlled fracturing method for increasing the fracturing complexity, which comprises the following steps:
(1) Evaluating key shale parameters and optimizing fracturing construction parameters;
(2) Putting a perforating gun into the coiled tubing for perforating operation;
(3) At 1.5m 3 Permin displacement Co-injection of Pre-treatment acid (15% HCl +2.0% corrosion inhibitor +1.5% cleanup additive +2.0% clay stabilizer +1.5% iron ion stabilizer) 20m 3 . Then at 5m 3 The discharge capacity of/min is injected with high-viscosity glue liquid 60m 3 And (4) replacing acid. The discharge capacity is reduced to 1m 3 Min, then continuously injecting high-viscosity slick water for 30m 3 Simultaneously, the discharge capacity is rapidly increased to 8m 3 /min。
(4) Injecting high-viscosity glue solution 60m 3 Make main seam and quickly raise its discharge capacity to 14m 3 /min。
(5) Injecting high-viscosity slick water containing 80-120 meshes of propping agent, wherein the viscosity is 18cp, and adding the 80-120 meshes of propping agent into the high-viscosity slick water in a plug manner according to the sand ratio of 1% -2% -3% -4% -5% 3 The sand carrying liquid volume of each slug is 35m 3 、45m 3 、45m 3 、50m 3 、50m 3 The liquid volume of each slug of the spacer fluid is 40m 3 、50m 3 、50m 3 、60m 3 、60m 3 ；
(6) Injecting high-viscosity slick water containing 40-70 mesh propping agent with the viscosity of 18cp, and continuously adding the 40-70 mesh propping agent into the water according to the sand ratio of 3% -4% -5% -6% to obtain a mixture with the particle size of 10.05m 3 The sand carrying liquid volume of each slug is 50m 3 、55m 3 、55m 3 、60m 3 The liquid amount of the slug spacer fluid in the first three sections is respectively 60m 3 、60m 3 、60m 3 ；
(7) Injecting high-viscosity glue solution 60m 3 Viscosity of 60cp, discharge capacity is increased to 16m 3 /min。
(8) Injecting into acid slickwater system.
(8.1) acidic slickwater 30m is injected 3 The viscosity is 5cp, and when the glue solution enters the stratum, the pressure amplitude is about 1MPa/min, which shows that the high-viscosity glue solution improves the net pressure in the seam.
(8.2) injecting acid slickwater containing 80-120 meshes of propping agent, wherein the viscosity is 5cp, and adding the 80-120 meshes of propping agent into the acid slickwater in a segmented plug mode according to the sand ratio of 6 percent to obtain 3.6m 3 Wherein the sand carrying liquid volume and the isolating liquid volume are both 60m 3 ；
(8.3) injecting acidic slick water containing gel breaker for 60m 3 Viscosity of 5cp;
(9) Repeating the steps 6-8 for the first time:
injecting low-viscosity slick water containing 40-70 mesh proppant, and continuously adding the 40-70 mesh proppant into the low-viscosity slick water according to the sand ratio of 6% -7% -8% -9% 3 The amount of sand-carrying liquid in each slug is respectivelyIs 60m 3 、55m 3 、55m 3 、50m 3 The liquid amount of the slug spacer fluid in the first three sections is respectively 60m 3 、60m 3 、60m 3 ；
Injecting high viscosity glue solution 90m 3 Viscosity of 60cp, discharge capacity of 17m 3 Min, when the glue solution enters the stratum, the pressure amplitude is about 1MPa/min, which shows that the high-viscosity glue solution improves the net pressure in the seam;
injecting acidic slick water for 30m 3 ；
Injecting acidic slick water containing 80-120 mesh proppant, and adding the 80-120 mesh proppant into the acidic slick water in a manner of blocking according to the sand ratio of 8 percent to obtain a mixture with the particle size of 4.8m 3 Wherein the sand carrying liquid volume and the isolating liquid volume are both 60m 3 ；
Injecting acidic slick water containing gel breaker to obtain 60m 3 The viscosity was 5cp.
And 6, repeating the steps 6 to 8 for the second time:
injecting high-viscosity slick water containing 40-70 mesh proppant with the viscosity of 18cp, and continuously adding the 40-70 mesh proppant into the high-viscosity slick water according to the sand ratio of 9% -10% -11% 3 The sand carrying liquid volume of each slug is 55m 3 、55m 3 、50m 3 、50m 3 The liquid amount of the slug spacer fluid in the first three sections is 60m respectively 3 、60m 3 、60m 3 ；
Injecting 120m of high-viscosity glue solution 3 The delivery capacity is quickly increased to 18m 3 Min, when the glue solution enters the stratum, the pressure amplitude is about 1MPa/min, which shows that the high-viscosity glue solution improves the net pressure in the seam;
injecting acidic slick water for 30m 3 ；
Injecting acidic slick water containing 80-120 mesh proppant, and adding the 80-120 mesh proppant into the acidic slick water in a manner of blocking according to the sand ratio of 10 percent to 6.0m 3 Wherein the sand carrying liquid amount and the isolation liquid amount are both 60m 3 ；
Injecting acidic slick water containing gel breaker to obtain 60m 3 The viscosity was 5cp.
(10) Injecting high viscosity slick water containing 40-70 mesh proppant with viscosity of 18cp, and mixing the 40-70 mesh proppant19.95m is added according to the proportion that the sand ratio is 10 to 11 to 12 to 13 percent 3 The sand adding mode corresponding to the former two sand-liquid ratios is slug sand adding, and the sand-carrying liquid volume of each slug is 50m 3 、45m 3 The quantity of the isolating liquid of each slug is 60m 3 The sand adding mode corresponding to the last four sand-liquid ratios is that the sand carrying liquid volume of each slug is 30m by continuous sand adding 3 、30m 3 、20m 3 、10m 3 。
(11) Injecting a displacement fluid comprising: 30m 3 High-viscosity glue solution (viscosity is 60 cp) and 45m 3 High viscosity slickwater (viscosity 18 cp).
(12) Putting a bridge plug and a perforating gun into the hole to perform bridge plug packing and perforating operation, and repeating the steps (2) to (11) until all sections are constructed;
(13) And drilling and plugging after pressing, returning, testing and solving the yield.
The pressure does not exceed the limited pressure in the well construction process, the sand adding amount and the liquid using amount both meet the design requirements, and after the well is put into production, the gas production rate is improved to a certain extent compared with that of an adjacent well, which shows that the invention can improve the reservoir transformation efficiency of a deep shale gas well under a narrow construction pressure window.
Claims (9)
1. A pressure control fracturing method for increasing fracture complexity of a deep shale gas well is characterized by comprising the following steps:
step 1, evaluating key shale parameters and optimizing fracturing construction parameters;
step 2, carrying out perforation operation;
step 3, carrying out acid treatment;
step 4, manufacturing a main seam by using high-viscosity glue solution;
step 5, injecting high-viscosity slick water carrying 80-120 meshes of propping agent;
step 6, injecting high-viscosity slick water carrying 40-70 meshes of propping agent;
step 7, injecting high-viscosity glue solution;
step 8, injecting an acidic slickwater system;
step 9, repeating the step 6 to the step 8 for more than two times;
step 10, injecting high-viscosity glue solution carrying 40-70 meshes of propping agent;
step 11, adopting displacement liquid to perform displacement operation, and then putting a bridge plug into the displacement liquid;
step 12, repeating the steps 2 to 11 until all sections of construction are finished, and finally drilling and plugging, flowback, testing and production solving after pressing;
when the high-viscosity glue solution is injected in the step 7, the discharge capacity is increased, and the liquid amount of the high-viscosity glue solution is gradually increased;
step 8 comprises the following substeps: step 8.1, injecting acidic slick water; step 8.2, injecting acidic slick water carrying 80-120 meshes of propping agent; step 8.3, injecting acidic slick water containing gel breaker; the viscosity of the acidic slippery water is 1 to 5cp.
2. The method as claimed in claim 1, wherein in step 3, the amount of acid is 10 to 20m 3 The discharge capacity of the injected acid is 1 to 1.5m 3 Per min, the displacement of the substituted acid is 4 to 6m 3 And/min, reducing the discharge capacity of the acid to the discharge capacity of the acid after the acid reaches the injection hole, and allowing the acid to enter the first cluster of holes for 8-10m 3 Then, the displacement of the substituted acid is increased to 6 to 8m 3 /min。
3. The method according to claim 1, characterized in that in the step 5, the sand is added in a plug type manner, the sand-liquid ratio is 1 to 2 to 3 to 4 to 5%, the liquid volume of the sand-carrying liquid in each sand-liquid ratio is 60 to 90% of the volume of the shaft, and the liquid volume of the isolation liquid is 1 to 1.1 times of the liquid volume of the sand-carrying liquid.
4. The method according to claim 1, wherein in step 6, the sand-liquid ratio is 3 to 4 to 5 to 6 percent, the liquid amount of the sand-carrying liquid in each sand-liquid ratio is 70 to 100 percent of the volume of the shaft, the sand-carrying liquid amount in the first 3 sand-liquid ratios is 1 to 1.5 times of the liquid amount of the isolation liquid, and the sand-carrying liquid amount in the last 1 sand-liquid ratio is continuously added.
5. The method of claim 1The method is characterized in that in step 7, the discharge capacity of the high-viscosity glue solution is 14 to 18m 3 The liquid volume of the high-viscosity glue solution is 1~2 times of the volume of the shaft.
6. The method of claim 5,
in step 8.1, the liquid volume of the injected acidic slick water is 50 to 60 percent of the volume of the shaft;
in step 8.2, the sand-liquid ratio is 4~8%, and the liquid amount of the acid slickwater is 1~2 times of the volume of the well bore;
in step 8.3, the amount of acidic slickwater containing the breaker is 1~2 times the wellbore volume.
7. The method according to claim 1, wherein, in step 9,
when the step 6 is repeated for the first time, the sand adding mode is slug sand adding, the sand-liquid ratio is 6 to 7 to 8 to 9, the liquid volume of the sand-carrying liquid under each sand-liquid ratio is 70 to 100 percent of the volume of the shaft, and the liquid volume of the displacement liquid corresponding to the first three sand-liquid ratios is 1 to 1.5 times of the liquid volume of the sand-carrying liquid; and/or
When the step 8 is repeated for the first time, the sand-liquid ratio adopted in the step 8.2 is 6-10%, and the rest conditions are unchanged.
8. The method according to claim 1, wherein, in step 9,
when the step 6 is repeated for the second time, the sand adding mode is slug adding, the sand-liquid ratio is 9 to 10 to 11, the liquid volume of the sand-carrying liquid under each sand-liquid ratio is 70 to 100 percent of the volume of the shaft, and the liquid volume of the displacing liquid corresponding to the first three sand-liquid ratios is 1 to 1.5 times of the liquid volume of the sand-carrying liquid; and/or
And when the step 8 is repeated for the second time, the sand-liquid ratio adopted in the step 8.2 is 8-12%, and the rest conditions are unchanged.
9. The method according to one of claims 1 to 8, characterized in that in step 10, the sand-to-liquid ratio is 10 to 11 to 12 to 13%; wherein, the first two sand-liquid ratios adopt slug type sand adding, the 1 st sand-liquid ratio is the 1 st slug, the sand-carrying liquid amount is 80 to 100 percent of the volume of the shaft, and the displacement liquid amount is equal to the volume of the shaft; the 2 nd sand-liquid ratio is the 2 nd slug, the sand-carrying liquid amount is 70 to 90 percent of the volume of the shaft, and the displacement liquid amount is equal to the volume of the shaft; and continuously adding sand into the last four sand-liquid ratios, wherein the sand-carrying liquid volume corresponding to each sand-liquid ratio is 20 to 50 percent of the volume of the shaft.
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