地表化探异常立体解释模型的建立及其意义--以库车坳陷米斯布拉克地区为例

以往对化探异常主要进行平面和剖面的二维解释,难以准确地反映化探异常与地下油气分布的关系。以库车坳陷米斯布拉克地区油气化探为例,系统研究了该区沉积—构造演化、生烃过程、油气运移特征及异常展布规律,并以油气垂向运移理论为指导,建立了该区化探异常立体解释模型(地质体模型、输导空间模型、异常压力模型和化探异常立体模型),直观反映了该区油气垂向运移的方式、动力来源、运移空间和运移路径,系统解释了米斯布拉克地区地表化探异常的形成过程及其与地下油气的关系,发现断裂面凸面引起的油气聚敛运移导致异常加强,而断裂凹面引起的油气发散运移导致异常减弱。总体来看,化探异常立体解释模型在米斯布拉克地区化探异常解释中取得了良好的效果,有效地提高了化探异常解释的确定性和准确性。

Establishment of three-dimensional interpretation model for surface geochemical anomaly:A case study of Meath Braque area in Kuqa Depression

In the past, the interpretation of oil and gas geochemical anomaly was primarily carried out by two?dimensional interpretation of plane and profile, which is difficult to accurately reflect the relationship between geochemical anomaly and subsurface oil and gas distribution. Taking oil and gas geochemical exploration in Meath Braque area of Kuqa Depression as an example and guided by vertical migration theory of oil and gas, the authors established a three?dimensional model for interpretation of geochemical anomaly ( comprising three?dimensional model of geology, transportation space, abnormal pressure and geochemical anomaly) on the basis of the study of sedimentary?tectonic evolution, hydrocarbon generation evolution, oil and gas migration characteristics and abnormal distribution law. It directly reflects the oil and gas vertical migration, power source, migration space and migration pathway, and systematically explains the formation process of surface geochemical anomaly and its relationship with underground oil and gas in Meath Braque area. It is found that convergent migration of oil and gas caused by the bulge fracture surface leads to anomaly intensification, and divergent migration of oil and gas caused by the concave facture fracture surface results in anomaly weakening. Overall, the three?dimensional interpretation model for geochemical anomaly has achieved good results in Meath Braque area and it effectively improves certainty and accuracy of the geochemical anomaly interpretation.