Mesozoic Reservoir And Trap Evaluation In Qingcheng Arch.

There are huge potential for exploration of Mesozoic in Qingcheng Arch. But due to the lack of systematic research for a long time, the extreme complexity of the basin evolution in Mesozoic, the uneven distribution of original formations and the denudation and alteration of previous sedimentary strata caused by later structure events, the overall understanding degree of oil and gas geological rules in this area is relatively low, which has seriously restricted the exploration process of this area. This paper has carried out systematic research on the Mesozoic strata, reservoir, tectonic movement and reservoir forming based on the theoretical guidance of tectonic geology, sequence stratigraphy, modern petroleum geology theory and etc, combined with the comprehensive application of drilling, logging, seismic data, core analysis and testing and production test data.We have established the sequence framework of Mesozoic in Qingcheng Arch based on study which has been carried out from two respects, macroscopic interface and microscopic interface. The main production strata Xiwa formation can be divided into two sub-members, the upper sub-member and the lower sub-member and the Mengyin formation can be divided into three sub-members, the upper, the middle and the lower. Through the analysis of tectonic evolution and stratigraphic distribution, this paper has determined the geological structure, which is there are two sets of faults controlling mountain forming and two tectonic systems controlling the strata, and has made clear the traps’ developing laws that are dominated by tectonic traps and stratigraphic traps. We have made analysis and prediction of Mesozoic reservoir development characteristics using method of the post-stack seismic inversion constrained by logging, finding out that reservoirs of Mesozoic in Qingcheng Arch are mainly distributed in Xiwa formation and the middle and the lower sub-member of Mengyin formation, with reservoirs less developed in the upper sub-member of Mengyin formation. By the analysis of effectiveness and oiliness of these traps, we have made clear the controlling factors of oil and gas reservoir forming of Mesozoic in Qingcheng Arch. The developmental condition and the spatial-temporal relationship of faults, unconformities and sand bodies determine the types and distributions of traps in this area. This paper has putted forward three target reservoir types, that are tectonic, strata and compound reservoir type. On the basis of the above study, we have determined the exploration plans and made integral deployment and evaluation of oil reservoirs of Mesozoic in Qingcheng Arch. 6 exploratory wells have been deployed. The incremental reserves of Mesozoic would be expected to amount to 2000 × 104 t. We have achieved good exploration effect.