数值模拟法研究高压气井试井流压上升原因

STUDY ON REASONS WHY THE FLOWING PRESSURE OF WELL TEST INCREASES WI TH NUMERAL SIMULATION FOR HIGH PRESSURE GAS WELLS

克 -依构造带高产气藏试井的流压上升现象 ,导致了克 -依构造带超高压气藏测试 (试井 )资料不能被有效解释。自喷井定产量试井流压下降与非自喷井流压上升的试井理论已较成熟 ,对于自喷井定产量试井流压上升的试井分析理论还没有人进行研究 ,文章研究了高压气井定产量试井导致流压上升的原因。根据渗流理论 ,建立了变表皮系数、高速非达西渗流、部分打开地层的数学模型 ;根据数值模拟理论 ,建立了差分方程 ;研制了数值模拟软件 ,用研制的数值模拟软件模拟了部分打开地层、高速非达西渗流、变表皮系数等因素的井底压力响应。在测试过程中地层损害程度在减轻 ,这是高压气井流压上升的主要原因 ,表皮系数降低得越多时 ,井底流压上升得越快。部分打开地层、高速非达西渗流单因素不能导致高压气井流压上升。这些认识对建立自喷井定产量试井流压上升的试井理论有重要意义。文章建立的高压气井试井流压上升的数值模拟方法可用来解释高压气井试井流压上升的资料。

Since the flowing pressure of well test increases for the high production gas reservoir in Ke-Yi structural belt, the well test data can not be interpreted effectively for the high pressure gas reservoir. The well test theory of the flowing pressure decreasing for blow wells testing, and the flowing pressure increasing for non-blow wells testing is mature. But, nobody is studying the theory of the flowing pressure increasing for blow wells testing. The article investigated the reasons why the flowing pressure increases during the production-deciding test for high-pressure gas wells. Based on the percolation theory, the mathematic model with variable skin factor, non-Darcy percolation caused by high velocity, and partly opened formation is developed. According to the numeral simulation theory, the difference equation is established, and the software of the numeral simulation is developed. With the software, the bottom-hole pressure response to the partly opened formation, the non-Darcy percolation caused by high velocity, and the variable skin factor is simulated. The formation damage level decreases during the production-deciding test, which is the main reason why the flowing pressure increases for high-pressure gas wells. The more the skin factor decreases, the faster the bottom-hole flowing pressure increases. The partly opened formation and the non-Darcy percolation caused by high velocity can't make the flowing pressure increasing of high-pressure gas wells separately. Such knowledge has important signification for the well test theory of the flowing pressure increases during the production-deciding test of blow wells. The numeral simulation for flowing pressure increasing of well test of high-pressure gas wells can be used to interpret the data of the flowing pressure increasing of well test of high-pressure gas wells.