The Main Controlling Factors Of Hydrocarbon Accumulation In Southern Central Uplift Buried Hills

On the basis of tectonic evolution research, main controlling factors of hydrocarbon accumulation were analyzed including buried hill texture, fracture, migration and conservation. Lithology composition, evolution chronology and logging identification were strengthened. Influence of multiple tectonism was highlighted to buried hill structure, traps, fracture development, hydrocarbon migration and accumulation. The control of relationship between source and reservoirs was stressed to hydrocarbon supplying manners, reservoir models and patterns. Five achievements and knowledge were obtained as shown below.1. Central Uplift evolution history and its strata belongings were straightened out.Premesozoic was weathered and eroded for its long-term uplift with a steady inner structure. In Mesozoic, tectonic movements became intense resulting in complex inner structure. Buried hill belt shape was formed preliminarily. Tectonic movement was similar in Cenozoic, buried hill belt shape was formed finally at the end of Dongying stage basically. Study shew that the strata Central Uplift belonged to Anshan group.2. Inner strata texture was defined for metamorphic rock. Lithology was constituted of metamorphic rocks and magmatic rocks. Metamorphic rock can be subdivided into three categories including25kinds, magmatic rocks into2categories with4kinds. Buried hill inner lithology distributes layer-like vertically and belt-like in east-west direction horizontally.3.Reservoir space, distribution and control factors were clarified. Fracture and intergranular pores dominated in crust while fractures in inner buried hills. Fractures developed well in whole buried hill belt for multiple tectonic movements, especially along marginal deep faults, large-scale fracture belts were found. Layer-like reservoir and sealing beds association exists in inner buried hills vertically.Fractures are controlled by advantage lithology series, intense long-term movement faults controlled formation and distribution of fractures, magma intrusion is advantageous for the development of fractures,weathering and erosion benefited crust reservoir.4.Main factors are identified for hydrocarbon accumulation. Inner layer-like reservoir and sealing bed combination is the key point for inner oil pool;deep faults provided regional oil-gas providing windows with source-reservoir joint fault planes; oil pool type and its character are decided by disposition of source and reservoir.Relationship played an important role in the formation of oil pools between finalization of buried hill shape and hydrocarbon migration period. Compound hydrocarbon migration passages were advantageous for inner oil pools. Integrated reservoir model was set up for crust and inner buried hills.5. Remarkable achievements were gained according to comprehensive research. Main exploration objects and subsequence region were clarified. Exploration block types were subdivided and main exploration objects were defined.9exploration wells were arranged among which5wells were drilled, commercial oil flows were found in3wells.49.52million tons of prognostic reserves were finished in2011and45.58million tons of probable reserves in2012, resulted in outstanding economic and social returns.