Forecast method and device for gas well productivity

Abstract

The invention provides a forecast method and device for gas well productivity, comprising the steps of establishing dynamic changing relationship between gas well pseudopressure and shale gas output according to the linear flow production dynamic model of gas well under volume fracture, the dynamic changing relationship contains multiple basic parameters and unknown parameters; determining the major fracture semi length of the multiple unknown parameters by using the historical production data of gas well, and using the major fracture semi length to update the dynamic changing relationship; based on the dynamic changing relationship after update, obtaining parameter restraint equation via identification method of featured flow segment; and using the probability distribution model of the basic parameter and the parameter restraint equation to calculate the remaining unknown parameters and probability distribution model of productivity evaluation parameter together with the relevant credible region; using the probability distribution model and the relevant credible region to forecast the gas well productivity according to the dynamic changing relationship after update. The forecast method and device for gas well productivity can quantify the productivity forecast risk.

Description

technical field [0001] The invention relates to the technical field of natural gas development, in particular to a method and device for predicting the productivity of shale gas wells. Background technique [0002] Gas well productivity evaluation, that is, production performance analysis, has always been one of the core tasks of reservoir engineers. After the gas well is officially put into production, use daily production dynamic data to analyze production characteristics, evaluate gas well parameters, evaluate (recoverable) reserves and predict gas well production, which can provide reliable information for early gas field production capacity construction and later production adjustment and optimization . [0003] At present, a more reliable productivity evaluation method is to comprehensively determine the rationality and reliability of reservoir parameters based on the calculation results of various decline analysis models. According to the different mathematical mode...

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Problems solved by technology

[0005] In addition, due to the generally low resolution of production data, many flow states of shale gas cannot be clearly reflected, which leads to the number of unknown parameters in the analytical model (such as formation-fracture parameters) being greater than the number of constraint equations (feature flow section), so the interpretation results of shale gas wells are multi-solution

Moreover, different interpretation results will have a great impact on the production forecast, and the shorter the production history, the greater the impact on the forecast parameters

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