| The onshore exploration area of Liaohe Depression is 6779 km~2,which is relatively smalle.With many years of exploration,the discovery degree of oil and gas has reached 53%,which is relatively high.The pressure of accomplishing the 10 million tons of stable production has become higher and higher.To meet the requirement of Liaohe Oilfield's prospecting to increase reserves,developing and stabilizing production,it is imperative to conduct research on the accumulation characteristics of tight oil deposit,promoting the development of superseding fields.Leijia region is located in the West Depression of Liaohe.It stretches from Changgu Well9 in the west to Chenjia Faults in the east,and from Shu Well 110 in the south to Gao Well 81in the north.The total area is about 300km2.The lithology in the research zone is complicated and various carbonates in the thin-interbedded form cover on the housing bubble basalt.At the same time,volcanic breccia develops near the fault in that zone.After many periods of faulting and basement movement,the volcanic breccia and all kinds of carbonate rocks in the study region grows to form a good reservoir.Meanwhile,the southeast of the research area is close to Chenjia source sub-sag with good oil source conditions.Since 2008,the exploratory well in Leijia area in the Sha-4 Section of the compact layer has had good oil and gas shows.With the unceasing deepening of research for tight oil,in 2013,Lei Well 88 and Leiping Well 2 drilled in Leijia area obtained high-yield industrial oil and gas flow from Sha-4 Section in compact carbonate reservoir,showing the good prospect of exploration and development of tight oil in the research area.Starting from the characteristics of source rock and reservoir,this study evaluated the geochemical characteristics and hydrocarbon generation potential of the mud shale,and reservoir properties,oiliness and dominant lithology distribution of the reservoir stratum(lacustrine carbonate rocks and sandstone);Based on the analysis of successful exploration of wells,this research analyzes accumulation theory,main controlling factors and enrichment rules,establishes a comprehensive division and divides favorable area.The research contents include:(1)the establishment of geochemical characteristics of hydrocarbon rock source research and evaluation method;(2)characterization research of the tight reservoir;(3)research of the tight oil's accumulation mechanism;(4)research of the tight oil's accumulation mode;(5)resources evaluation and favorable area optimization.Through this research,the evaluation standards for high-quality hydrocarbon source rocks in Leijia area were set up;the sequence of dominant lithology in the reservoir of the fourth member of Shahejie Formation is determined.The sequence of dominant lithology of Dujiatai oil reservoir is:mud crystal dolomite containing mud?analcime mud crystal dolomite containing mud?muddy rock containing analcime?mudstone containing analcime.The sequence of dominant lithology of Gaosheng oil reservoir is:grain dolomite?grain mud crystal dolomite containing mud?mud crystal dolomite?dolomitic shale;Establish the critical diagram of the flow state of oil in the tight reservoir;Establish the tight oil accumulation models in Leijia region.The major two are unconventional continuity and conventional structure lithologic oil and gas;The tight oil resource scale is determined.Basin modeling method,microfacet volume method,analogy method and Delphi comprehensive method are respectively applied in the estimate of the tight oil resource volume at Shasi section in Leijia area in Liaohe Depression.The geological tight oil resource volume is determined to be 221million tons,which is comparatively large in resource potential;Optimization of the favorable areas for exploring tight oil can define the direction for further exploring tight oil and gas. |
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