Method for predicting recoverable reserves and evaluating development effect of gas drive reservoir

Abstract

The invention discloses a method for predicting recoverable reserves and evaluating a development effect of a gas drive reservoir. The method comprises: starting from an oil-gas two-phase seepage law,based on an exponential function relationship of gas-oil relative permeability, through a material balance equation and a Darcy law, deducing and establishing a novel gas-drive characteristic curve relation between the gas-oil ratio and accumulated oil under the condition of stable seepage of a gas-drive development oil field, reducing use of uncertain parameters, and providing a reliable oil reservoir engineering method for calculation of recoverable reserves in the middle and later periods of gas-drive oil field development; furthermore, drawing a gas-drive oil reservoir development effectevaluation chart through gas-drive characteristic curve derivation, the chart visually describing the internal relation among the gas-oil ratio, the recovery degree and the recovery ratio, and providing a basis for evaluation of the effects of oil field measures, comprehensive adjustment and the like.

Description

technical field [0001] The invention relates to the technical field of petroleum development reservoir engineering, in particular to a method for predicting recoverable reserves of gas drive reservoirs and evaluating development effects. Background technique [0002] The water drive characteristic curve is one of the important methods for predicting the recoverable reserves of water drive reservoirs and evaluating the development effect. After more than 70 years of research, there are currently more than 30 types of water drive characteristic curves, including A, B, C, and D The four most efficient characteristic curves are incorporated into industry standards. These four water flooding curves have unique application values ​​in oilfield work because of their different applicable fluid viscosity ranges. In gas drive reservoirs, Yang Guoxu (1995) proposed for the first time that the cumulative gas production G p and cumulative oil production N p It is a gas drive character...

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Problems solved by technology

However, compared with water drive curves, the number of gas drive characteristic curves is far from enough, and the existing gas drive characteristic curves still need to calculate DN p The size of +C, this parameter is related to oil and gas viscosity, volume coefficient, irreducible water saturation, crude oil geological reserves, etc. The combination of static and dynamic data is complex

On the other hand, the currently established chart for gas drive reservoirs is similar to Tong's standard water drive curve chart, which shows the relationship between the dimensionless gas fraction and the degree of recovery. It is easy to understand and accept as the medium moisture content, but its application is limited and it is difficult to promote

In short, there is only one gas drive curve currently used for performance prediction and evaluation of gas drive reservoirs, and this method still has many limitations. Based on the accumulated rich dynamic production data, the establishment of a more concise and practical gas drive reservoir evaluation method is of great significance for the efficient development of gas drive oil fields

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