Shale gas well productivity evaluation and prediction method

Abstract

The invention discloses a shale gas well productivity evaluation and prediction method. The method comprises the following steps: an expression of a differential equation of a single-phase seepage mathematical model is obtained; the differential equation is solved and represented by a pressure form to obtain a seepage velocity and output formula; a deliverability equation is determined through fitting production data; the derived output formula is arranged to obtain a shale gas horizontal well staged fracturing output formula; boundary pressure (pe) required to be known can be known from the shale gas output formula; and as shale gas has the influences of absorption and desorption, a deviation factor is required to be corrected to obtain formation pressure of a shale gas reservoir. The prediction method deduces the deliverability equation for a shale vertical well and a horizontal well according to the desorption and dispersion characteristics of the shale gas, so that a shale gas output evaluation method is built, the precise output prediction is obtained, and the economic efficiency is improved.

Description

technical field [0001] The invention relates to a method, in particular to a shale gas well productivity evaluation and prediction method, which belongs to the field of shale gas exploration. Background technique [0002] Shale gas is an unconventional natural gas that occurs in organic-rich mud shale and its interlayers. It mainly exists in adsorption and free states. The main component is methane. It belongs to the same category as "coalbed methane" and "tight gas". . The formation and enrichment of shale gas has its own unique characteristics, and it is often distributed in thick and widely distributed shale source rock formations in the basin. Shale gas has been recognized by people for a long time, but it is more difficult to collect than traditional natural gas. With the increasingly scarce resources and energy, as a beneficial supplement to traditional natural gas, people gradually realize the importance of shale gas. Shale gas exists in kerogen, clay particles and ...

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Problems solved by technology

[0004] The purpose of the present invention is to overcome the problem that the above-mentioned existing prediction methods have large prediction errors, which lead to the investment in shale gas wells and the income obtained cannot meet the design requirements, resulting in serious economic losses. A shale gas well productivity evaluation is designed. According to the characteristics of shale gas desorption and diffusion, the prediction method deduces the productivity equations of shale vertical wells and horizontal wells respectively, so as to establish a shale gas productivity evaluation method, obtain accurate productivity prediction, improve economic efficiency, and solve The existing prediction method has a large prediction error, which leads to the problem that the investment and income obtained in shale gas wells cannot meet the design requirements, resulting in serious economic losses.

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