四川威远地区页岩气藏储层纵向可动用程度分析

Analysis of Vertical Producing Degree for Shale Gas Reservoirs in Weiyuan Area,Sichuan

四川威远地区页岩气近8年的开发实践表明,页岩气井产量与龙一11小层钻遇率呈正相关关系,因此目前威远地区水平井目标靶体位置均优选在龙一11小层。但由于龙一11小层厚度较薄,仅动用该小层储量无法实现效益开发。因此,如何准确获取体积压裂后压裂缝高度,对进一步评价该地区页岩储层纵向可动用程度以及剩余气分布至关重要,而目前获取压裂缝高度尚无直接有效的手段。通过岩心分析和微地震监测等直接观察和预测手段,通过平台动用储量情况分析和压裂施工过程分析等生产、监测数据分析手段,通过数值模拟和压裂模拟等模拟手段,多种方法相互结合、相互验证,综合分析预测威远地区页岩储层压裂缝高度约15m左右,纵向可动用层位为龙一11~龙一13小层。而龙一14小层几乎未动用,是目前剩余气分布的主要层位,可优选为下步立体开发的目标层位。

The shale gas development practice in Weiyuan area of Sichuan Province in the past eight years shows that there is a positive corrrelation between the production of shale gas wells and the drilling rate of Longyi11 sublayer,so the target location of horizontal wells in Weiyuan area is preferred in Longyi11 sublayer.However,due to the thinness of Longyi11 sublayer,it is impossible to achieve profitable development only by exploiting the reserves of this sublayer.Therefore,how to accurately obtain the fracture height after stimulated reservoir volume is crucial to further evaluate the vertical producing degree and remaining gas distribution of shale reservoirs in this area.However,there is no direct and effective method to obtain the fracture height at present.Through direct observation and prediction means such as core analysis and micro-seismic monitoring,production and monitoring data analysis means such as platform producing reserves analysis and fracturing process analysis,and simulation means such as numerical simulation and fracturing simulation,the fracture height of shale reservoirs in Weiyuan area is about 15m after various methods are combined and verified for comprehensively analyzing and predicting.The vertical produceability layers are Longyi11-Longyi13 sublayers.However,Longyi14 sublayer,which is almost unproductive,is the main horizon of remaining gas distribution at present,and can be selected as the target horizon for the next tridimensional development.