川南裂缝性有水气藏压力恢复试井解释及应用

INTERPRETATION AND APPLICATION OF PRESSURE BUILDUP TEST OF FRACTURED WATER-CARRYING GAS RESERVOIRS IN SOUTH SICHUAN

川南裂缝性有水气藏具有小型化、有水和封闭性的特点 ,一口井就是一个单独的裂缝系统 ,同一构造、同一气藏上有很多的裂缝系统 ,裂缝系统之间相互独立、互不连通 ,难以形成规模较大的整装气田 ,气井投产时间先后不一 ,产能建设视气藏储量和产能而定 ,采用滚动勘探开发方式 ,这给气藏开发工作带来了较大的困难 ,在气藏试采和产能建设之前 ,摸清气藏储量和产能是经济有效开发气藏的关键。为此 ,文章对气藏储量和产能的计算方法进行了研究 ,但是现有的方法大部分局限于气藏开发的中后期 ,而早期根据压力恢复试井资料计算气藏储量和简易评估气井产能方法的研究 ,成果相对较少。通过对利用压力恢复试井资料计算储量和产能的方法作了专题研究 ,提出了适合于川南地区裂缝性有水气藏计算储量和产能的气藏早期储量预报的对数差值法和确定气井无阻流量的方法。该方法已在川南气田广泛应用 ,效果显著。

The fractured water-carrying gas reservoirs in South Sichuan are of the properties as small size,water-bearing and confinement,etc.A well is an independent fracture system and there are many fracture systems in the same structure and/or the same gas reservoir.These fracture systems are independent or disconnected from each other so that it is difficult to form a large-sized integral gas field.Owing to the fact that the periods of gas-wells' being put into production are different,a progressive exploration and development scheme had to be adopted,which causes great difficulty for gas reservoir development because the productivity establishment is dependent upon the reserves and deliverability of the gas reservoir.Therefore it is the key of developing gas reservoir economically and effectively to make a thorough investigation of the reserves and deliverability of the gas reservoir before the production test and productivity establishment of the gas reservoir.For this reason,the calculation methods of the reserves and deliverability of the gas reservoir were studied by the authors.Most of the existing methods,however,are localized to be used for the gas reservoir development in medium and late stages,and only a few results involve the researches on calculating the reserves of gas reservoir and evaluating the deliverability of gas well simply in terms of pressure buildup test data.Through studying the methods of calculating the reserves and deliverability by use of the pressure buildup test data,the authors propose the logarithmic difference method of forescasting early gas reservoir reserves used for calculating the reserves and deliverability of the fractured water-carrying gas reservoirs in South Sichuan and the way of determining the open-flow capacities of gas wells in this region.These methods are widely applied to the gas fields in South Sichuan with obvious effectiveness.