砂体连通性评价在隐蔽圈闭预测中的应用

砂体的空间连通规模是决定可形成岩性圈闭的大小和丰度的重要因素，通过单井砂体统计分析，多井井间测井克里格内插砂体对比方法，对准噶尔盆地西北缘侏罗系进行分层序的砂体空间通性评价，并运用砂岩百分含量平面分布预测岩性圈闭的有利区带。研究取得以下认识：①低的砂岩百分含量有利于形成岩性圈闭，但不利条件是砂岩的单层厚度小，开成较大规模的岩性圈闭较难；②以相对等时界面作约束条件，测井井间克里格插值可以大大提高砂体对比的精度；③在整个侏罗系Ⅱ级层序中，分别处于Ⅱ级层序湖侵期和最大湖泛期的Ⅲ级层序B、C有利于形成岩性圈闭，他别处于Ⅱ级层低位期和高位期的Ⅲ级层序A、D则较难以形成岩性圈闭；④岩性圈闭有利区带常处在砂岩百分含量总体较低且向上倾方向快速降低的地带。

Application of Sand Connectivity Evaluation in Prediction of Subtle Traps

Sand connecting scale in space is a key factor controlling size and abundance of lithologic trap.This paper presents statistical analysis of single well sand body and correlation of multi-well sand bodies integrated interwell logs with Kriging interpolation metrod,by which the connectivity evaluation of sequential sand spaces of Jurassic in northwestern margin of Junggar basin has been made,predicting fa-vorable zones of the lithologic trap applying lateral distribution of sand content technique.Several conclusions are then drawn as follows:1)low sand content is favorable for forming lithologic trap,but thin sand thickness is hard to form large scale of lithologic trap;2)taking relative isochronal horizon as a restricting condition,interwell log with Kriging interpolation can remarkably increase the accuracy of sand correlation;3)in Grade II sequence of Jurassic,it is much easier to form lithologic traps in Grade III sequences of B and C,which lie in lake-transgressing period and the maximum lake-flooding period of Grade II sequence,respectively,while it is more difficult to form lithologic traps in Grade III sequences of A and D,which lie in lowstand and highstand periods of the Grade II sequence,respectively;4)the favorable zones forming litho-logic traps are often located in areas with low sand content and quick declining toward updip direction.