Method for calculating effective exploitation permeability lower limits of low-permeability clastic rock reservoir

Abstract

The invention discloses a method for calculating effective exploitation permeability lower limits of a low-permeability clastic rock reservoir. The method comprises the following steps: A, drawing a relation chart of the unit thickness daily fluid production rate and the mean permeability of the low-permeability reservoir of all depth intervals; B, establishing a chart that economic limit initial produced oil is changed with burial depths of the reservoir and the crude oil price; C, calculating permeability which corresponds to the mid-depth of the low-permeability reservoir of different exploitation thicknesses; D, repeating the step C according to the divided longitudinal distribution depth intervals of the low-permeability reservoir, and calculating the effective exploitation permeability lower limits, which correspond to the mid-depths of remaining depth intervals, under the constraints of the economic limit initial produced oil of the low-permeability clastic rock reservoir of different exploitation thicknesses; then, establishing a function relationship between the effective exploitation permeability lower limits and the burial depths under the constraint of the economic limit initial produced oil of the low-permeability reservoir of different exploitation thicknesses. By adopting the method disclosed by the invention, by taking the economic limit initial produced oil and the exploitation thicknesses are constraint conditions, different effective exploitation permeability lower limits can be determined at the same depth according to the difference of the exploitation thicknesses.

Description

technical field [0001] The invention relates to oil and gas exploration and development technology, in particular to a method for obtaining the lower limit of effective development permeability of low-permeability clastic rock reservoirs. Background technique [0002] The lower limit of effective development permeability of clastic rock reservoirs refers to the minimum permeability of reservoirs that can store and seepage fluid, and can produce hydrocarbons that meet the minimum economic benefits under the existing technological conditions. [0003] With the continuous improvement of oil and gas exploration, the target of clastic rock oil and gas exploration and development gradually shifts to low permeability, ultra-low permeability and ultra-low permeability reservoirs. Permeability is the key factor determining the seepage characteristics and development effect of low-permeability reservoirs. It is of great significance to study the lower limit of effective development pe...

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Problems solved by technology

[0006] 1) Oil testing method, distribution function curve method, minimum effective pore throat radius method, irreducible water saturation method, oil testing method, empirical statistics method, relative permeability method, drilling fluid invasion method, porosity-permeability intersection method, The commonly used methods for obtaining the lower limit of reservoir effective development permeability, such as oil-bearing occurrence method and production capacity method, do not consider the influence of factors such as production pressure difference, production thickness, and initial oil production on the economic limit on the lower limit of effective reservoir development permeability;

[0007] 2) The test method takes into account the influence of production pressure difference, development thickness and other factors on the lower limit of permeability, but does not consider the influence of economic limit initial oil production with depth and crude oil price on the lower limit of effective development permeability of the reservoir;

[0008] 3) Some scholars have obtained the lower limit of the effective development permeability of gas reservoirs by using the productivity simulation experiment method. However, because the simulation experiments mostly use one-way fluid flow to simulate the divergent fluid flow around the actual geological conditions and the heterogeneity of low-permeability reservoirs There is a large difference between the experimental results and the actual geological conditions due to the differences between the temperature and pressure conditions of the simulated experiment and the continuous change of the actual formation temperature and pressure conditions.

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