准噶尔盆地乌夏地区三叠系油气成藏控制因素分析

Controlling Factors of Triassic Oil and Gas Accumulation in Wuerhe-Xiazijie Area,NW Junggar Basin

准噶尔盆地乌夏断裂带三叠系油气资源丰富,其成藏受多种因素控制。对该区控制油气成藏的各种因素进行了综合分析,指出:断裂在不同时期对油气的聚集具有不同的控制作用;地层不整合面往往成为油气运移的重要通道和油藏聚集成藏带;三叠系扇三角洲相和冲积扇相是该区有利储集体发育的主要沉积相带;乌夏地区三叠系油藏具有多套储盖组合,三叠系克拉玛依组和白碱滩组是主要的区域盖层;三叠系油藏大都为发育在鼻隆构造背景上的岩性地层油藏,这种受构造背景控制的岩性地层油气藏是该地区三叠系油气的主要成藏模式。

Triassic oil sources of the Wuerhe-Xiazijie fault belt are abundant, but the accumulation is controlled by composite factors. This paper analyzes the controlling factors： （1） The fault occurrence in different eras have different effects on the oil and gas accumulation; （2） Unconformity surfaces are usually major hydrocarbon migration channels and the belts of hydrocarbon accumulation; （3） The Triassic fan delta faceis and the alluvial fan facies are favorable reservoir blocks in this region; and （4） The Triassic oil reservoirs in the Wuerhe-Xiazijie area possess multiple reservoir-seal assemblages, and the Karamay Formation and the Baijiantan Formation are major regional cap rocks. Comprehensive analysis shows that Triassic oil reservoirs are mainly lithologic and stratigraphic oil reservoirs, which occurred in the background of nose-uplift structure. The key reservoir-orming rule in this area is that lithologic and stratigraphic oil reservoirs are controlled by structure background.