Characteristics Of Structure, Reservoir And Hydrocarbon Accumulation Of Lower Palaeozoic Buried Hill In Zhuanghai, Shengli Oil Field

Oil and gas exploration in buried hill has been a hot issue and is of great significance in finding oil and gas resources.Due to its a complex structure, multivariated strata, plural reservoir and diversity hydrocarbon accumulation, Lower Paleozoic buried hill in Zhuanghai area was characterized based on seismic data, well logs and core description. We applied a fine structure interpretation technology. Firstly, each reflection horizon was characterized by using horizon calibration technique; Secondly, faults were interpreted by using modeling and strata configuration, and then, coherence analysis was applied to confirm faults assemblage in plane, following interpreting horizons by the characteristics of reflection horizons. Finally, a fine structure imaging was formed by using variable-speed imaging technique.The characteristics of buried hill structure, reservoir and oil-gas pools were studied with the comprehensive technique. Two types matching work was performed: fine structure interpretation in buried hill and geophysical prediction in carbonate reservoir of Low Paleozoic. Hence, we established three kinds of models on lower Paleozoic buried hill, which include growth of structure, growth of reservoir and hydrocarbon accumulation. Each block was evaluated with grey association evaluation and favorable exploration directions were pointed out.The result of fine structure interpretation indicated the faults include inside and outside of the area formed four groups of faults, with directions of NW-strike, nearly NS-strike, NE-strike and NEE-strike, three fracture systems were developed from deep to shallow at the same time. Deep fracture systems were bases of division of east and west buried hills, middle-level fracture constituted the division of Mesozoic buried hill, shallow fracture forms the division of Shanghais, Change, Shaanxi buried hill. This area has experienced five tectonic movements which can be divided into eight structural evolutional stages, formed multiply fold-belt that the fold hill coexisted with hammock hill and fault-block hill. The buried hill of Shanghais belongs to inside folded-detachment buried hill as a whole, it has five kinds of structural styles, and they are the overthrust nappe, the compaction fold, the superposed overthrust, the decoupling detachment and the strike-slip faultA synthetically prediction method was developed to predict reservoirs of Low Paleozoic in Shanghais area by using the following techniques include reservoir modeling, structure analysis of microfracture, finite element prediction of fissured reservoir and fracture prediction technology through 3D-MOVE structural forward and inverse. We applied karsts geochemistry method to analyze the formation mechanism of pore space of the lower Paleozoic reservoirs. Lower Paleozoic buried hill accumulate spaces in Zhuanghai area is controlled by multiple factors. Karstification, dolomitization and fracturing were the main factor for lower Paleozoic buried hill accumulate spaces, and paleogeomorphology together with ancient river system controlled the karsts developing in later Yanshanian period. By analysis, we established three kind development models of karsts reservoir, they are the karsts upland original is now become a fault-convex zone, the karsts upland original is now become a fault-concave zone and the high-stand lake of karsts slope original is become a fault-convex zone.Compared with Futai, Zhuangxi, Chengdao buried hills, we established the hydrocarbon accumulation model of the lower inside folded-detachment buried hill of lower Paleozoic, which is'multi-source hydrocarbon, fault-fold control, straightforward filling, same direction enrichment'. We evaluated the optimized traps for hydrocarbon accumulation in the buried hill.