Sandstone reservoir self-diverting acidizing method

A self-steering and acid-steering technology, which is applied to chemical instruments and methods, mining fluids, earthwork drilling, etc., can solve the problems of high construction cost, poor acidizing effect of heterogeneous sandstone reservoirs, and low content of soluble matter. Achieve the effect of easy operation

Inactive Publication Date: 2016-10-26
CHINA NAT OFFSHORE OIL CORP +2
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Problems solved by technology

[0002] For sandstone reservoirs, there are mainly three conventional acidizing and diverting technologies: one is to use packer tools to selectively divert and acidify wells with large intervals between layers or perforation intervals, so that most of the wells with vertical heterogeneity The reservoir has been effectively improved, but at the same time there are great limitations. On the one hand, due to the strong heterogeneity of the formation during the conventional acidizing process, the acid liquid is likely to "finger" in the large pores and fractures of the high-permeability layer, which cannot make the low-permeability layer On the other hand, for wells with small distances between layers or perforation sections, it is impossible to use tools to pack and acidify wells. Third, the process of lifting and unloading packers is cumbersome and the construction cost is high.
The second is to use granular temporary plugging and diverting agents for diversion acidification, mainly including sodium benzoate and phenolic resin, but these two types of chemical substances also have limitations during construction. To achieve the ideal temporary plugging and diversion effect, at the same time, as soon as the solid phase particles enter the wellbore during the construction process, solid phase cakes will form on the well wall and cannot enter the high-permeability pores to achieve the ideal temporary plugging and diversion effect
The third is t

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Examples

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Embodiment 1

[0033] Embodiment 1: Taking the indoor simulation experiment of cores in Bozhong SZ36-1 oilfield of CNOOC as an example, the detailed description will be given.

[0034] Flow experiments using parallel dual cores with different permeability are used to simulate the fluid permeability in the reservoir due to the heterogeneity of the reservoir under formation conditions. 1# core: core length 7cm, diameter 2.54cm, porosity 27.5%, permeability 683×10 -3 μm 2 , 2# core: core length 7cm, diameter 2.54cm, porosity 9.6%, permeability 38×10 -3 μm 2 . To simulate the reservoir conditions, the diversion acidizing flow experiment was carried out at a temperature of 60°C and a confining pressure of 1 MPa, according to the principle of "injecting base fluid→injecting diverting acid→injecting treatment fluid→injecting postfluid→injecting replacement fluid→injecting base fluid" Injection sequence, simulating the flow process of the well fluid entering the reservoir during the diversion ac...

Embodiment 2

[0043] Embodiment 2: Taking the indoor simulation experiment of cores in Bozhong SZ36-1 oilfield of CNOOC as an example, the detailed description will be given.

[0044] Flow experiments using parallel dual cores with different permeability are used to simulate the fluid permeability in the reservoir due to the heterogeneity of the reservoir under formation conditions. 3# core: core length 7cm, diameter 2.54cm, porosity 21.5%, permeability 487×10 -3 μm 2 , 4# core: core length 7cm, diameter 2.54cm, porosity 13.6%, permeability 98×10 -3 μm 2 . To simulate the reservoir conditions, the diversion acidizing flow experiment was carried out at a temperature of 90°C and a confining pressure of 1 MPa, according to the principle of "injecting base fluid→injecting diverting acid→injecting treatment fluid→injecting postfluid→injecting displacement fluid→injecting base fluid" Injection sequence, simulating the flow process of the well fluid entering the reservoir during the diversion ...

Embodiment 3

[0079] Example 3: Caofeidian 11-6 Oilfield D16H well, field operation of diverting acid in detail.

[0080] Well D16H is a horizontal well, which was put into production on March 15, 2008. The length of the horizontal section is 202m, and the effective thickness of the average production layer is 8m. For the uniform distribution of layers, it is necessary to use the way of turning to achieve uniform distribution of acid. The sequence of construction operations is as follows: injecting pre-fluid → injecting treatment fluid → injecting post-fluid → injecting pre-fluid → injecting treatment fluid → injecting post-fluid → injecting pre-fluid → injecting treatment fluid → injecting post-fluid → injecting replacement fluid .

[0081] D16H well diversion diversion acidification of all the weight percentage of each well fluid:

[0082] Steering acid (preflux): 13% hydrochloric acid, 6% diverting agent, 1% corrosion inhibitor, 1% iron ion stabilizer, 1% clay stabilizer, 1% drainage a...

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Abstract

The invention discloses a sandstone reservoir self-diverting acidizing method, which comprises the following steps of (1) injecting diverting acid into a sandstone reservoir to be used as ahead liquid; (2) injecting processing liquid into the sandstone reservoir; (3) injecting subsequent liquid into the sandstone reservoir; and (4) injecting displacing liquid into a pit shaft, and jacking acid liquid in the pit shaft into the deep path of the reservoir. The diverting acid is prepared from the following ingredients including 12 to 15 percent of HCl, 3 to 10 percent of diverting agents, 4 to 8 percent of additives and the balance water, wherein the diverting agents are erucyl amide hydroxysulfobetaine; the processing liquid is various kinds of conventional processing liquid suitable for sandstone acidizing; the subsequent liquid is prepared from the following ingredients including 5 to 15 percent of HCl, 1 to 2 percent of gel breakers, 4 to 8 percent of additives and the balance water; the displacing liquid is diesel oil, gasoline or 3-percent ammonium chloride solution. The percentage of the ingredients is mass percentage. The sandstone reservoir self-diverting acidizing method has the advantages that the uniform acid distribution effect of the acid liquid in the reservoir can be improved; the subsequent gel breaking residue is reduced; and the inhomogenous reservoir acidification is realized.

Description

technical field [0001] The invention relates to a method for improving the acidification effect of heterogeneous sandstone reservoirs in the process of matrix acidification in the field of oil and gas field development, in particular to a method for self-steering and split flow acidification of sandstone reservoirs. Background technique [0002] For sandstone reservoirs, there are mainly three conventional acidizing and diverting technologies: one is to use packer tools to selectively divert and acidify wells with large intervals between layers or perforation intervals, so that most of the wells with vertical heterogeneity The reservoir has been effectively improved, but at the same time there are great limitations. On the one hand, due to the strong heterogeneity of the formation during the conventional acidizing process, the acid liquid is likely to "finger" in the large pores and fractures of the high-permeability layer, which cannot make the low-permeability layer On the...

Claims

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Application Information

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IPC IPC(8): E21B43/27E21B33/138C09K8/74
CPCC09K8/74E21B33/138E21B43/26
Inventor 刘义刚杜娟刘长龙孟祥海赵立强刘平礼高尚兰夕堂山金城李年银张继伟高建崇张岺罗志锋
Owner CHINA NAT OFFSHORE OIL CORP
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