产量不稳定法评价气井渗透率和表皮系数方法研究

Evaluation of Permeability and Skin Factors of Gas Well by Using Rate Transient Method

渗透率是评价储层物性以及气井产能的一个重要参数,而表皮系数是表征井筒污染程度的唯一参数,这2个参数在气井动态分析中的作用至关重要。目前求取这2个参数的主要方法是试井,尤其是不稳定试井。然而由于试井费用较高,再加上生产任务紧张,靖边气田绝大部分的气井不能进行关井测试,致使无法全面了解储层特性以及增产措施的效果。运用产量不稳定法计算气井渗透率和表皮系数,并与试井解释结果进行了对比,对比结果表明产量不稳定法具有一定的解释精度,可以作为试井的补充。该方法在实践中得到了检验,解释的结果被应用于数值模拟的参数场建立、复杂地质边界诊断、增产措施的效果评价以及二次改造井的优选。

Permeability was one of the important parameters for evaluating reservoir physical property and deliverability of gas wells,and skin factor was the only parameter characterizing the pollution degree of wellbore.The two parameters played the most important role in analyzing gas well performance.The main method to calculate the parameters was well testing,especially pressure transient testing.However,due to the higher costs of well testing,and heavy production tasks,shut-in tests were not conducted at most gas wells in Jingbian Gas-field,so that the reservoir characteristics and the effect of stimulation were not fully recognized.In this paper,the rate transient method is presented to analyze production data to calculate permeability and skin factors of the gas wells and the results are compared with that of well test interpretation,it shows that results are accurate and can be as a supplement of well test.The results can be applied to establishment of parameter field in numerical simulation,diagnosis of complex geological boundaries,evaluation of the effect of stimulation and wells optimization for reconstructed wells.