什股壕区带西部盒3段构造-岩性复合圈闭识别与评价

Recognition and evaluation on structural-lithological compound trap of Shihezi 3 Member,western Shiguhao play,Or⁃dos Basin

为了对鄂尔多斯盆地什股壕区带西部二叠系下石盒子组盒3段构造-岩性复合圈闭进行识别与评价,证实该区已取得的天然气勘探成果,有效地寻找油气聚集有利区带,以该区盒3段为研究对象,分析了盒3段砂体展布特征与顶面构造特征,指出了实钻井砂体发育及所处构造位置。研究结果表明:①盒3段构造-岩性复合圈闭含气性概率主要介于0.20~0.31;②含气概率介于0.25~0.50,为低风险圈闭,含气性级别划分为Ⅰ类,含气性概率介于0.10~0.25,为中等风险圈闭,含气性级别划分为Ⅱ类;③该区带盒3段实钻井钻探成果同时受砂体与构造的双重因素控制,即砂体与构造叠合形成了油气聚集的有利圈闭;④以圈闭含气性评价为基础,分析了圈闭条件、烃源岩与充注条件、储层条件、保存条件,得出了盒3段构造-岩性复合圈闭含气性评价结果。结论认为:①在什股壕区带西部盒3段识别出构造-岩性复合圈闭13个;②什股壕区带西部盒3段含气性级别划分为2类,含气性级别为Ⅰ类的圈闭7个,含气性级别为Ⅱ类的圈闭6个。

In order to recognize and evaluate the structural-lithological compound trap of the Lower Permian Shihezi 3 Member,western Shiguhao play,Ordos Basin,confirm the exploration achievements,and search for some favorable hydrocarbon-accumulating zones,the Shihezi 3 Member was taken as an objective to analyze some characteristics on both sandbody distribution and top surface structure.Then,one place with sandbody developed in the actual wells and its structural location were make clear.Results show that(1)for this member in this play,the gas-bearing probability is mainly between 0.20 and 0.31;(2)one compound trap with the probability ranging from 0.25 to 0.50 belongs to a low-risk trap and its gas-bearing level is classified as type I.Another trap with the probability varying from 0.10 to 0.25 is taken as a medium risk trap and its gas-bearing level is classified as type II;(3)drilling practice may be affected jointly by sandbody and structure,implying that the superimposition of sandbody and structure may result in a favorable trap for hydrocarbon accumulation;(4)based on evaluation on the gas-bearing property,the source rock,charging,reservoir,and preservation are analyzed to obtain the property of Shihezi 3 Member.In conclusion,there are totally 13 structural-lithological traps recognized.What’s more,the gas-bearing property of Shihezi 3 Member can be classified into two levels,including 7 traps with gas-bearing level I and 6 traps with gas-bearing level II.