采用两种实验方法进行气藏岩芯应力敏感研究

STUDY ON CORE STRESS SENSITIVITY FOR GAS RESERVOIR WITH TWO EXPERIMENT METHOD

目前实验室测定岩芯应力敏感性通常采用变外压恒内压方式测试,该测试方法与气田实际开发过程中上覆岩层压力不变,流体压力变小的实际情况不符合,提出了变内压恒外压测试方法,采用苏里格低渗岩芯在地层温度条件下进行变内压恒外压测试和变外压恒内压测试。研究表明:变内压恒外压测试比变外压恒内压测试应力敏感性更弱,随多次应力敏感次数增加,应力敏感性变弱,甚至趋于一个极限。为气井动态分析提供了实验依据,对研究低渗气藏相对高、中、低渗岩芯在多次升降压过程中的应力敏感特征有重要意义。

Core stress sensitivity test in lab generally use Change Outside Pressure & Keep Inside Pressure Test method at present, which is not accord with actual gas field development process that overburden pressure do not change while fluid pressure decrease. This paper put forward Change Inside Pressure & Keep Outside Pressure Test method and use Sulige gas field low permeability core do Change Outside Pressure & Keep Inside Pressure Test and Change Inside Pressure & Keep Outside Pressure Test at the condition of formation temperature. Study indicate that core stress sensitivity of Change Inside Pressure & Keep Outside Pressure Test is little than Change Outside Pressure & Keep Inside Pressure Test, core stress sensitivity become more little even tend to a limit with multiple stress sensitivity times. This provides experiment accordance for gas well dynamic analysis and has very important meaning for study on stress sensitivity character of low permeability gas reservoir relative high、medium、low permeability core during multiple stress rise and drop process.