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CN-122014199-A - Acid fracturing modification method and device for complex lithology carbonate reservoir

CN122014199ACN 122014199 ACN122014199 ACN 122014199ACN-122014199-A

Abstract

The invention relates to the technical field of carbonate rock transformation, in particular to an acid fracturing transformation method and device of a complex lithology carbonate rock reservoir, wherein the method comprises the steps of bridge plug segmentation of the complex lithology carbonate rock reservoir; and sequentially injecting fracturing fluid A, acid fluid B, fracturing fluid B and fracturing fluid C into the reservoir after bridge plug segmentation, and/or sequentially injecting fracturing fluid A, acid fluid B and fracturing fluid B to form artificial cracks, so that physical properties and seepage capability of a reservoir matrix are improved, and potential damage of excessive corrosion of the acid fluid to the reservoir is reduced. According to the invention, the hydraulic fracture and acid corrosion fracture transformation effect is considered, the fracturing fluid is used for making a fracture to communicate with the matrix, and the high-displacement injection of the acid fluid with certain concentration is used for improving the physical properties and seepage capability of the matrix of the reservoir, so that the fracture diversion capability of the reservoir is not influenced, the effectiveness of the artificial fracture is improved, the damage of the acid fluid to the reservoir caused by excessive corrosion is reduced, and the volume of the reservoir transformation and the fracture diversion capability with different scales are improved.

Inventors

  • LI ZHENXIANG
  • WANG WEI
  • WANG YONGJUN
  • LI FENGXIA
  • Zhang Kuangming
  • DAI JUNQING
  • LI RANGBIN
  • Jin Mindong

Assignees

  • 中国石油化工股份有限公司
  • 中国石油化工股份有限公司勘探分公司

Dates

Publication Date
20260512
Application Date
20241112

Claims (10)

  1. 1. An acid fracturing modification method of a complex lithology carbonate reservoir is characterized by comprising the following steps: Bridge plug segmentation is carried out on the complex lithology carbonate reservoir; and sequentially injecting fracturing fluid A, acid fluid B, fracturing fluid B and fracturing fluid C into the reservoir after bridge plug segmentation, and/or sequentially injecting fracturing fluid A, acid fluid B and fracturing fluid B to form artificial cracks, so that physical properties and seepage capability of a reservoir matrix are improved, and potential damage of excessive corrosion of the acid fluid to the reservoir is reduced.
  2. 2. The method of claim 1 wherein the bridge plug segments have a single segment perforation cluster count of 6-8 clusters, a pitch of 10-50m for each cluster, and a single segment size of 1600-1800m 3 .
  3. 3. The method of claim 1, wherein the artificial fracture has a length of 140-160m and a height of 44-48m.
  4. 4. The method according to claim 1, wherein the viscosity of the fracturing fluid A is more than 25 mPa.s, the injection displacement is 20-22m 3 /min, and the injection volume is 250-300m 3 ; The viscosity of the fracturing fluid B is 8-15 mPa.s, the injection displacement is 16-18m 3 /min, and the injection liquid amount is 150-200m 3 ; The viscosity of the fracturing fluid C is 10-20 mPa.s, the injection displacement is 8-10m 3 /min, and the injection liquid amount is 100-150m 3 .
  5. 5. The method according to claim 1, wherein the viscosity of the acid solution A is 1.5-3.0 mPa.s, the injection displacement is 16-18m 3 /min, and the injection volume is 150-200m 3 ; The viscosity of the acid liquid B is 0.1-1.0 mPa.s, the injection displacement is 16-18m 3 /min, and the injection liquid amount is 90-150m 3 .
  6. 6. The method of claim 1, wherein the fracturing fluid A is a guar fracturing fluid, and comprises the following components, by mass, 0.3-0.5% of hydroxypropyl guar, 0.05-0.2% of sodium carbonate, 0.2-0.4% of a cross-linking agent, 0.05-0.2% of a cleanup additive, 0.02-0.04% of a breaker, and the balance of water; The fracturing fluid B is slick water, the composition formula of the fracturing fluid B in mass percent is 0.10-0.20% of resistance reducing agent, 0.05-2.0% of cleanup additive, 9-11% of propping agent and the balance of water; the fracturing fluid C is slick water, the composition formula of the fracturing fluid C in mass percent is 0.1-0.3% of resistance reducing agent, 0.05-2.0% of cleanup additive, 9-11% of cleanup additive and the balance of water.
  7. 7. The method according to claim 1, wherein the acid liquor A is a noracid, and the formula of the acid liquor A comprises, by mass, 4-5% of hydrochloric acid, 0.05-0.07% of a thickening agent, 1.0-3.0% of an acid corrosion inhibitor, 0.05-2.0% of an iron ion stabilizer, 0.05-2.0% of a drainage aid and the balance of water.
  8. 8. The method according to claim 1, wherein the acid liquor B is a composite organic acid, and comprises the following components, by mass, 3-5% of formic acid, 1-3% of acetic acid, 0.5-2% of chelating acid, 1.0-3.0% of acid corrosion inhibitor, 0.05-2.0% of iron ion stabilizer, 0.05-2.0% of cleanup additive, and the balance of water.
  9. 9. The method of claim 6, wherein the proppant is a 40/70 mesh ceramsite; The diameter of the temporary plugging ball is 22-25mm, or the particle size is 20-40 meshes.
  10. 10. An acid fracturing modification apparatus for a complex lithology carbonate reservoir, comprising: the bridge plug segmentation module is used for bridge plug segmentation of the complex lithology carbonate reservoir; And the injection module is used for sequentially injecting the fracturing fluid A, the acid fluid B, the fracturing fluid B and the fracturing fluid C into the reservoir after the bridge plug is segmented, and/or sequentially injecting the fracturing fluid A, the acid fluid B and the fracturing fluid B to form artificial cracks, so that physical properties and seepage capability of a reservoir matrix are improved, and potential damage of excessive corrosion of the acid fluid to the reservoir is reduced.

Description

Acid fracturing modification method and device for complex lithology carbonate reservoir Technical Field The invention relates to the technical field of carbonate rock transformation, in particular to an acid fracturing transformation method and device for a complex lithology carbonate rock reservoir. Background The conventional carbonate acid fracturing processes at home and abroad at present comprise common acid fracturing, pre-acid fracturing, closed acid fracturing, balanced acid fracturing, multi-stage injection acid fracturing and the like, and according to the continuous deepening of reservoir characteristics, the processes of clean self-steering acid fracturing, compound acid fracturing, ultra-large repeated acid fracturing, hydraulic injection segmented acid fracturing, network fracture acid fracturing and the like are developed in recent years, so that the acid fracturing modification technical requirements of different types of carbonate reservoirs are better met. For acid fracturing working fluid systems, namely acid liquor, the acid fracturing working fluid systems generally comprise common hydrochloric acid, gelled acid, cross-linked acid, emulsified acid, self-rotating acid, self-generating acid and other types of viscoelastic surfactants, and the acid fracturing working fluid systems mainly fulfill the aims of delaying the reaction rate of acid rocks, prolonging the acting distance of the acid liquor, reducing the filtration loss and the like. The basic acid liquid is mainly industrial hydrochloric acid with the concentration of 15-28%. Although various acid liquor systems are developed to meet different reservoir characteristics at present, as the carbonate rock exploration and development work goes deeper, challenges are continuously presented to conventional acidizing and fracturing modification technologies for carbonate rock reservoirs with high temperature, deep depth, complex lithology and the like, and new acid liquor systems are required to meet modification requirements. The reservoir rock quality of the stucco limestone type carbonate rock of the two-stage system of the Szechuan basin is complex, the oil reservoir temperature is high, quartz scraps and the like in the rock and clay minerals are easily deposited after acid etching due to the complex rock quality in the acid pumping process, so that the flow conductivity of cracks formed by acid etching is reduced, and the yield and the stable yield of oil and gas are affected. Based on the technical background, the invention researches an acid fracturing modification method and device of a complex lithology carbonate reservoir. Disclosure of Invention Aiming at the defects of the prior art, the invention provides an acid fracturing modification method and device for a complex lithology carbonate reservoir, which have the advantages of taking the hydraulic fracture and acid etching fracture modification effects into consideration, making a fracture by using fracturing fluid to communicate with a matrix, injecting acid liquor with a certain concentration in a double-slug way at high discharge capacity to improve physical properties and seepage capacity of the reservoir matrix, and simultaneously, not influencing the fracture diversion capacity of the reservoir, so as to improve the effectiveness of artificial fractures, reduce the potential damage of the acid liquor due to excessive corrosion to the reservoir, and be beneficial to improving the volume of reservoir modification and the diversion capacity of the fractures with different scales, increasing the acid fracturing modification range and effect of the reservoir, and improving the yield and stable production effect of an oil gas well. To achieve the above object, a first aspect of the present invention provides a method for acid fracturing modification of a complex lithology carbonate reservoir, comprising: Bridge plug segmentation is carried out on the complex lithology carbonate reservoir; and sequentially injecting fracturing fluid A, acid fluid B, fracturing fluid B and fracturing fluid C into the reservoir after bridge plug segmentation, and/or sequentially injecting fracturing fluid A, acid fluid B and fracturing fluid B to form artificial cracks, so that physical properties and seepage capability of a reservoir matrix are improved, and potential damage of excessive corrosion of the acid fluid to the reservoir is reduced. A second aspect of the invention provides an acid fracturing modification apparatus for a complex lithology carbonate reservoir, comprising: the bridge plug segmentation module is used for bridge plug segmentation of the complex lithology carbonate reservoir; And the injection module is used for sequentially injecting the fracturing fluid A, the acid fluid B, the fracturing fluid B and the fracturing fluid C into the reservoir after the bridge plug is segmented, and/or sequentially injecting the fracturing fluid A, the acid fluid B and the fracturing fl