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Carbonate reservoir multistage alternating acid fracturing displacement optimization method

A technology for carbonate reservoirs and optimization methods, which is applied in earthwork drilling, production fluids, boreholes/well components, etc., can solve problems such as lack of consideration of reservoir factors, improve acid fracturing effects, and increase drainage The effect of increasing the flow area and increasing the length

Active Publication Date: 2019-12-31
CHENGDU NORTH OIL EXPLORATION DEV TECH
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Problems solved by technology

[0004] The purpose of the present invention is to provide a method for optimizing the displacement of multi-stage alternating acid fracturing in carbonate rock reservoirs, so as to solve the problem that the displacement of multi-stage alternating acid fracturing in the prior art is based on the performance of ground equipment and lacks consideration of reservoir factors. In order to realize the optimization of the displacement parameters of multi-stage alternating acid fracturing based on the face-to-volume ratio and improve the effect of acid fracturing

Method used

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  • Carbonate reservoir multistage alternating acid fracturing displacement optimization method
  • Carbonate reservoir multistage alternating acid fracturing displacement optimization method
  • Carbonate reservoir multistage alternating acid fracturing displacement optimization method

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Embodiment 1

[0038] Such as figure 1 A method for optimizing displacement of carbonate reservoirs by multi-stage alternating acid fracturing includes the following steps:

[0039] (a) Calculating the surface-to-volume ratio of the reservoir to be acid fractured Among them, S: Reaction area of ​​reservoir rock; V: Volume of acid liquid participating in the reaction;

[0040] Specifically, the reservoir types are classified first, and different formulas are used to calculate fundamentally different classification results:

[0041] If the reservoir flow channel is a pore, then Where d is the average diameter of the pores, and L is the average length of the pores;

[0042] If the reservoir flow channel is a horizontal fracture, then where R f is the average radius of the horizontal crack, W is the crack width;

[0043] If the reservoir flow channel is a double-wing vertical fracture, then Where W is the width of the crack, H is the height of the crack, and L is the length of the s...

Embodiment 2

[0052] Such as figure 1 A method for optimizing displacement of carbonate reservoirs by multi-stage alternating acid fracturing is shown. On the basis of Example 1, the dosage of the pre-fluid and acid fluid is increased step by step. The pre-fluid is 3%-15% hydrochloric acid solution. The total amount V of prefluids at all levels satisfies V=V'+V p , where V' is the volume of hydrochloric acid solution required to dissolve the carbonate rock within each meter of the radial range of the wellbore per unit thickness of the reservoir; V p is the total volume of pores after removal of carbonate rocks per unit thickness of the reservoir.

[0053] in, is the volume of carbonate rocks per meter in the radial direction of the wellbore, and X is the solvency. Solvency X is equal to the volume of rock divided by the volume of hydrochloric acid solution consumed. V 0 is the original pore volume of the reservoir per unit thickness.

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Abstract

The invention discloses a carbonate reservoir multistage alternating acid fracturing displacement optimization method. The optimization method comprises the following steps that (a) a surface-to-volume ratio of a reservoir to be subjected to acid fracturing is calculated, wherein S is the reaction area of reservoir rock, and V is the volume of an acid solution participating in a reaction; (b) themaximum construction displacement which can be borne by the reservoir is calculated in combination with the surface-to-volume ratio; (c) according to the bearing ability of a ground device, the actualconstruction displacement is determined; and (d) according to the acid pressure design scheme, the amount of each stage of prepad fluid and the acid solution is determined; and the amount of each stage of the prepad fluid and the acid solution is correspondingly divided by the actual construction displacement, and the injection time of each stage of the prepad fluid and the acid solution is obtained. According to the carbonate reservoir multistage alternating acid fracturing displacement optimization method, the problem that in the prior art, the displacement of multistage alternating acid fracturing is based on the performance of the ground device and lacks of consideration of reservoir factors is solved, the purposes that displacement parameters are optimized based on the surface-to-volume ratio of multistage alternating acid fracturing, and the effect of acid fracturing is improved are achieved.

Description

technical field [0001] The invention relates to the field of acid fracturing to increase production, in particular to a method for optimizing the displacement of carbonate rock reservoirs by multi-stage alternating acid fracturing. Background technique [0002] Acid fracturing refers to squeezing the acid liquid into the reservoir at a pressure higher than the fracture pressure of the reservoir or the closing pressure of the natural fracture, forming fractures in the reservoir, and at the same time, the acid liquid reacts with the rock on the fracture wall and etches the fracture wall non-uniformly. Grooved or uneven etched fractures are formed in the rock. After the construction, the fracture walls are not complete, and finally artificial fractures with a certain geometric size and conductivity are formed to improve the seepage status of oil and gas wells, thereby increasing the production of oil and gas wells. Acid fracturing generally does not use proppant, but relies on ...

Claims

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Application Information

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IPC IPC(8): E21B43/27
CPCE21B43/26
Inventor 李登金肖勇徐兵周宗明黄海平吕新东孙照磊程洋万丽娟黄凯杜新龙袁浩杨鸿邓强徐超刘家材
Owner CHENGDU NORTH OIL EXPLORATION DEV TECH
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