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CN-122014197-A - Advanced acid fracturing sand fracturing composite transformation method for carbonate reservoir

CN122014197ACN 122014197 ACN122014197 ACN 122014197ACN-122014197-A

Abstract

The invention belongs to the technical field of oil and gas reservoir transformation, and particularly relates to a carbonate reservoir deep acid fracturing sand fracturing composite transformation method. The method mainly comprises the following steps of (1) a pre-acid pre-fracturing stage, (2) a sand fracturing main joint making stage and a secondary sand carrying stage, (3) a multistage combined acid deep acid fracturing and replacing sand conveying stage, (4) a sand fracturing secondary joint making stage, a main sand carrying stage and (5) a displacement liquid displacing stage. The invention can be widely applied to the transformation of carbonate reservoirs, integrates the advantages of deep acid fracturing and sand fracturing, increases the crack volume of the carbonate reservoirs, adopts a multistage sand adding mode to replace sand feeding, and effectively improves the acid etching-supporting composite seam net diversion capability.

Inventors

  • Yang Shangru
  • LIU XIAORUI
  • LU HONGJUN
  • LIU HANBIN
  • XIE YONGGANG
  • CHEN BAOCHUN
  • ZHOU CHANGJING
  • MA ZHANGUO
  • XIAO YUANXIANG
  • GU YONGHONG

Assignees

  • 中国石油天然气股份有限公司

Dates

Publication Date
20260512
Application Date
20241112

Claims (10)

  1. 1. The method for carrying out deep acid fracturing and sand fracturing composite transformation on the carbonate reservoir is characterized by comprising the following steps of: S1, preprocessing a carbonate reservoir by using a pre-acid; s2, adopting a low-viscosity fracturing fluid to make a joint on the pretreated carbonate reservoir, and carrying sand by a multistage sand adding method to obtain a composite joint net system; S3, carrying out multistage combined acid deep acid fracturing and taking over sand conveying on the composite slotted net system to enable a carbonate reservoir to be deeply eroded, so as to obtain an acid etched composite slotted net system; S4, adopting a high-viscosity fracturing fluid to make a seam on the acid etching composite seam net system, carrying sand by a multistage sand adding method, and obtaining the acid etching-supporting composite seam net system; S5, displacing the high-viscosity fracturing fluid by using a displacement fluid to finish fracturing construction; the high-viscosity fracturing fluid is guanidine gum fracturing fluid with viscosity of more than 30 mPa.s, and the low-viscosity fracturing fluid is slickwater with viscosity of 3-5 mPa.s.
  2. 2. The carbonate reservoir deep acid fracturing composite transformation method is characterized in that the pre-acid in S1 is single-phase acid, the mass fraction of each component of the single-phase acid is 20% -25% of hydrochloric acid HCl, 2.0% -3.0% of retarder, 0.1% -0.2% of drag reducer, 0.3% -0.5% of cleanup additive, 1.5% -2.0% of corrosion inhibitor, 0.5% -1.0% of iron ion stabilizer and the balance of water, and the discharge capacity is 2.0% -4.0 m 3 /min.
  3. 3. The method for carrying out deep acid fracturing and sand fracturing composite transformation on a carbonate reservoir according to claim 1 is characterized in that the concrete implementation mode in the step S2 is that a low-viscosity fracturing fluid is adopted to inject the carbonate reservoir with large discharge capacity to form main cracks, branch cracks and micro cracks, a multistage sand adding method is adopted, and a high-viscosity fracturing fluid is utilized to carry small-particle-size propping agent at first and then carry medium-particle-size propping agent to semi-fill and seal the micro cracks and the branch cracks, so that a composite fracture network system is obtained; The range of the large-displacement injection is 8-10 m 3 /min; The small-particle-size propping agent is 70-140-mesh ceramsite or quartz sand, and the medium-particle-size propping agent is 40-70-mesh ceramsite or quartz sand; the half-pack is about 30-50% of the proppant volume by total fracture volume.
  4. 4. The carbonate reservoir depth acid fracturing sand fracturing composite transformation method of claim 3, wherein the multi-stage sand fracturing method is characterized in that the multi-stage sand fracturing method is characterized in that 70-140 meshes of quartz sand is adopted for crack sections far away from a shaft, 40-70 meshes of quartz sand is adopted for crack sections close to the shaft, and 2-4 stages of sand adding modes are adopted for each multi-stage sand adding mode for hierarchical injection.
  5. 5. The carbonate reservoir depth acid fracturing and sand fracturing composite transformation method is characterized in that the specific implementation mode of S3 is that a clean self-steering acid and hydrochloric acid multi-stage injection mode is adopted to realize carbonate reservoir depth corrosion, acid etching holes are formed, and the corrosion crack width and length are increased, so that an acid corrosion composite fracture network system is obtained.
  6. 6. The carbonate reservoir deep acid fracturing and sand fracturing composite transformation method is characterized in that the mass fractions of the components of the clean self-diverting acid are 20% of HCl, 1.2% -1.5% of surface active thickener, 1.0% of iron ion stabilizer, 1.5% -2.0% of high-temperature corrosion inhibitor, 2.5% of high-temperature corrosion inhibition auxiliary agent and the balance of water.
  7. 7. The carbonate reservoir depth acid fracturing composite transformation method is characterized in that the injection level in S3 is 4-6, the injection displacement is 4.0-6.0 m 3 /min, and the hydrochloric acid is 20% -25% hydrochloric acid.
  8. 8. The carbonate reservoir depth acid fracturing sand fracturing composite transformation method is characterized in that the specific implementation mode of the S4 is that a high-viscosity fracturing fluid large-displacement injection acid etching composite fracture network system is adopted, quartz sand pumped in the S2 is conveyed to the depth of a crack; The high-viscosity fracturing fluid in the step S4 is guanidine gum fracturing fluid with the viscosity of more than 30 mPa.s; The range of the large-displacement injection in the step S4 is 8-10 m 3 /min; The coarse grain diameter propping agent in the step S4 is 20-40 mesh ceramsite or quartz sand; and the medium-grain-diameter propping agent in the step S4 is 40-70-mesh ceramsite or quartz sand.
  9. 9. The carbonate reservoir depth acid fracturing sand fracturing composite transformation method is characterized in that a main crack section of the multistage sand fracturing method in the step S4 adopts 40-70 meshes of quartz sand and a branch crack section adopts 20-40 meshes of quartz sand and a multistage sand adding mode, and each multistage stage adopts 2-4 stages of sand adding modes for hierarchical injection.
  10. 10. The carbonate reservoir depth acid fracturing and sand fracturing composite modification method is characterized in that the displacement fluid in S5 is low-viscosity slickwater of 3-5 mPas.

Description

Advanced acid fracturing sand fracturing composite transformation method for carbonate reservoir Technical Field The invention belongs to the technical field of oil and gas reservoir transformation, and particularly relates to a carbonate reservoir deep acid fracturing sand fracturing composite transformation method. Background The carbonate reservoirs at home and abroad are rich in oil and gas resources, and considerable oil and gas resources are found in carbonate strata such as Huidos basin, sichuan basin, tarim basin and the like in China. Carbonate reservoirs generally have strong heterogeneity and complex pore-fracture systems, and reservoir reformation is an important means for achieving high and stable production of carbonate reservoirs. The method for reforming the carbonate reservoir at home and abroad mainly comprises ① matrix acidification, acid fracturing/deep acid fracturing of near-well carbonate to form cracks with diversion capability, acid fracturing/deep acid fracturing of ②, acid fracturing and uneven etching of the cracks to form acid-etched crack channels, such as a pre-hydraulic acid fracturing technology, a multi-stage injection acid fracturing technology, a solid acid fracturing technology, a closed acidification technology, a volume acid fracturing technology and the like, ③ cross-linked acid sand carrying acid fracturing, combining acid-etched cracks of the acid fracturing with support cracks of the sand adding fracturing to form an acid-etched-support composite crack network with higher diversion capability, and ④ sand adding fracturing, and filling the non-reactive fluid-created cracks with a supporting agent to form the diversion channels. The acid fracturing modification of the carbonate reservoir has the advantages of better communicating non-communicated pores and natural cracks and high construction success rate, but also has the disadvantages of uniform etching of high-ash carbonate, poor rock properties caused by acid rock reaction, high acid rock reaction rate caused by high reservoir temperature, serious acid fluid loss and the like. The support cracks formed by sand fracturing have more durable and effective diversion capability compared with acid fracturing transformation, but also have the defects of high fracture pressure of carbonate reservoirs, high construction difficulty, difficult communication and communication, natural cracks, difficult acid backflow and the like. Disclosure of Invention The invention aims to solve the problems of high reaction rate and severe acid liquor filtration caused by acid rock reaction, high fracture pressure of the carbonate reservoir, high construction difficulty, difficult communication and non-communicated pores, natural cracks and difficult acid flowback caused by sand fracturing, which are caused by the modification of the existing carbonate reservoir, so that the invention combines the advantages of acid fracturing and sand fracturing of the carbonate reservoir, and provides a composite modification method for deep acid fracturing and sand fracturing of the carbonate reservoir, so as to better solve the problem of carbonate reservoir modification. In order to achieve the above purpose, the invention adopts the following technical scheme: a carbonate reservoir deep acid fracturing and sand fracturing composite transformation method comprises the following steps: S1, preprocessing a carbonate reservoir by using a pre-acid; s2, adopting a low-viscosity fracturing fluid to make a joint on the pretreated carbonate reservoir, and carrying sand by a multistage sand adding method to obtain a composite joint net system; S3, carrying out multistage combined acid deep acid fracturing and taking over sand conveying on the composite slotted net system to enable a carbonate reservoir to be deeply eroded, so as to obtain an acid etched composite slotted net system; S4, adopting a high-viscosity fracturing fluid to make a seam on the acid etching composite seam net system, carrying sand by a multistage sand adding method, and obtaining the acid etching-supporting composite seam net system; and S5, displacing the high-viscosity fracturing fluid by using a displacement fluid to finish fracturing construction. The pre-acid in the S1 is single-phase acid, and the mass fraction of each component of the single-phase acid is 20% -25% of hydrochloric acid HCl, 2.0% -3.0% of retarder, 0.1% -0.2% of drag reducer, 0.3% -0.5% of cleanup additive, 1.5% -2.0% of corrosion inhibitor, 0.5% -1.0% of iron ion stabilizer and the balance of water, wherein the discharge capacity is 2.0% -4.0 m 3/min. Injecting a low-viscosity fracturing fluid into a carbonate reservoir with large discharge capacity to form main cracks, branch cracks and micro cracks, adopting a multistage sand adding method, and carrying a small-particle-size propping agent with large discharge capacity of the high-viscosity fracturing fluid, and then carrying a medium-particle-size propping agen