鄂尔多斯盆地大牛地气田丛式水平井组开发效果评价

Evaluation of development effect of cluster horizontal wells in Daniudi gas field,Ordos Basin

大牛地气田优质储量动用殆尽,剩余未动用储量品位低,直井有效开发难度大。针对致密砂岩储层非均质性强、有效砂体规模小、储量丰度低、单井产量低等一系列问题,水平井在非常规油气开发中具有显著的技术优势,丛式水平井组作为水平井整体开发模式之一,对水平井开发效果起着非常重要的作用。采用数值模拟方法和动态评价方法相结合,对比大牛地气田水平井组各开发阶段压降速率和单位压降产气量,开展气田同层(或异层)二井式、四井式、六井式丛式水平井组开发效果评价。研究表明:采用丛式水平井组开发,保证水平段延伸方向与最大主应力方向夹角大于60°,满足井组间最小距离大于500 m的条件时,同层井组部署以两井式反向为主,异层井组部署可采用两井式、三井式或四井式,可实现"三低"气田的规模效益开发,为鄂尔多斯盆地同类天然气资源量和国内外其它同类型致密低渗边际气田经济有效动用提供借鉴。

Almost all the quality gas reserves of Daniudi gas field have been produced. The remaining gas reserves are low in quality,thus cannot be developed efficiently with vertical wells. Considering the strong heterogeneity,limited sizes of effective sandbodies,low reserves abundance and low single well production rate of the tight sandstone layers,horizontal wells are preferred for the development of the remaining gas reserves. Cluster horizontal well group plays a key role in the practical production. Numerical simulation and dynamic evaluation are integrated to evaluate the exploitation performance of Daniudi gas field with different patterns of cluster horizontal well groups by comparing the pressure drawdown rate and gas production per pressure drop unit. The results demonstrate that the angle between the laterals and maximum principal stress should be larger than 60 degrees,and the minimum distance between these wells should be greater than 500 meter when using horizontal wells cluster group as the development strategy. These understandings will provide a useful reference for the exploitation of similar tight marginal gas fields in Ordos Basin and other basins.