Title: CONDITIONS OF GAS POOLING IN CARBONIFEROUS IGNEOUS ROCKS IN WELLBLOCK CAI-25,WUCAIWAN DEPRESSION,THE JUNGGAR BASIN
Abstract: Although industrial gas flow had been tested in the well Cai-25 in the Carboniferous igneous rock reservoirs in the Wucaiwan depression, the Junggar basin, several of the appraisal wells drilled later were dry holes. Therefore, it is urgent to study the controlling factors of hydrocarbon distribution in the study area. In view of the unique features of hydrocarbon pooling in igneous rock reservoirs, the factors controlling the formation of gas reservoirs are analyzed in respects of the characteristics of reservoir development, conditions of hydrocarbon migration and accumulation and the structural setting of the discovery well. The results show that the igneous gas reservoirs in the wellblock Cai-25 mostly underlie the top unconformity of the Carboniferous igneous rocks, and their lithologies are mainly of tuff, volcanic breccia and altered andesite, with fractures and various dissolution pores developed. The hydrocarbons generated by the Carboniferous dark mudstone and carbonaceous mudstone underlying the igneous rocks migrated upward along faults to the top of the igneous rocks and then migrated laterally through the permeable layers under the unconformity and accumulated in local structural highs, forming lithologic reservoirs in a structural high setting. Fault pathways, structural high background and poroperm characteristics of the igneous rocks are the major factors controlling gas pooling.
Publication Year: 2008
Publication Date: 2008-01-01
Language: en
Type: article
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