Reservoir gas tightness evaluation method

Abstract

The invention provides an oil reservoir gas tightness evaluation method. The oil reservoir gas tightness evaluation method includes the steps that 1, fine oil reservoir description is conducted on a target research area to complete establishment of a geological model; 2, fault blockage capability evaluation is conducted to evaluate the fault leakage position and the risk level; 3, numerical simulation is adopted for fitting production data of the elastic energy production phase, and the change rule of elastic energy along with time is calculated according to an oil reservoir engineering method; 4, the output of dissolved gas in the elastic production phase of an oil reservoir and the stock of dissolved gas in the oil reservoir are calculated; 5, the tightness of the oil reservoir to gas iscomprehensively evaluated according to the deficit and surplus degree of the dissolved gas. In the oil reservoir gas tightness evaluation method, the deficit and surplus degree of the dissolved gas is calculated according to the material balance principle, the tightness of the oil reservoir to the dissolved gas at the initial stage of development is judged according to the deficit and surplus degree of the dissolved gas, and then the tightness of the oil reservoir to other kinds of gas is indirectly judged.

Description

technical field [0001] The invention relates to the technical field of oilfield development, in particular to a method for evaluating the gas tightness of an oil reservoir. Background technique [0002] In the development and design of artificial gas injection, it is necessary to first evaluate the ability of the reservoir to seal gas. If the injected gas leaks along the fault, it will not be able to effectively supplement the formation energy, let alone oil and gas displacement. At the same time, during the gas injection construction, the excessive gas injection will cause the risk of fault opening. [0003] Gas has a stronger flow capacity than oil-water liquid. Even if the production dynamic data can prove that faults have a good sealing ability for oil-water, the risk of leakage of injected gas cannot be ruled out. Existing evaluation methods for fault sealing performance, such as shale smear factor (SSF), mud ratio (SGR), lithology configuration, principal stress direc...

AI Technical Summary

Problems solved by technology

If the injected gas leaks along the fault, it will not be able to effectively supplement the formation energy, let alone oil and gas replacement. At the same time, during the gas injection construction, the excessive gas injection will cause the risk of fault opening

[0003] Gas has a stronger flow capacity than oil-water liquid. Even if the production dynamic data can prove that faults have a good sealing ability for oil-water, the risk of leakage of injected gas cannot be ruled out.

Existing evaluation methods for fault sealing performance, such as shale smear factor (SSF), mud ratio (SGR), lithology configuration, principal stress direction, etc., are mostly based on the combined characterization of static parameters, and the calculation results can only predict the fault in the The level of leakage risk at a certain location, lack of deterministic evaluation results

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