Accumulation Model In The Graben Of Kong Xi Fault Zone In Huanghua Depression

The Huanghua Depression is located in the middle of the Bohai Bay Basin.It is that a Cenozoic faulted basin developed on the Mesozoic basin.The east and west sides are sandwiched by Chengning uplift and Cangxian uplift,and the northern end is connected with the Yanshan fold belt.In this study,the Kongxi fault zone is located in the Kongnan area of the Kongdian tectonic zone in the Huanghua Depression,which belongs to a third tectonic unit in the basin.The Zaoyuan Oilfield is composed of the main area of the Kongxi fault zone.In the process of exploration in the Kongxi fault zone,the high structural part of the Kongxi fault zone was mainly regarded as the key area of exploration in the past.With the increase of exploration and development degree,found a favorable target is increasingly difficult.There is a new breakthrough in our work of exploration in the low part of the Kongxi fault zone,which provides a new way for the exploration work in this area.Based on the structural characteristics of Kongxi fault zone,the paper analyzed activity and evolution process of the Kongxi fault zone,summed up the evolution mechanism of the Kongxi graben zone,made it clear that the coupling relationship between the Kongxi graben zone and factors of hydrocarbon accumulation,and established graben accumulation model of the Kongxi fault zone.The proposal of above model is a breakthrough of the thinking formulary that high fault zone structure parts of the fault zone is favorable area for petroleum exploration.This research has important practical significance for petroleum exploration of the region,and also has some degree of guiding significance to the further exploration and development of high mature blocks of the old oil region.The main works and achievements study of the study are as follows:1.Three graben zones were established in the Shenjiapu area of the Kongxi fault zone.From the large background analysis,the evolution mechanism of the graben zone was affected by the interaction between the Pacific plate and the Eurasian plate in the Cenozoic period.The overlap of the extensional and strike-slip stresses in this area was due to change in the subduction direction of the Pacific plate.From the local tectonic background analysis,the evolution of the graben belt was directly controlled by the Fenghuadian fault and the Kongxi fault.The Kongxi fault played a more important role than the Fenghuadian fault.The Kongxi fault has the characteristics of segmentation of activity,and the activity of each sections are obviously different.The Kongxi fault and the Fenghuadian fault intersects at the bottom,forming there grabens in the south,middle and north.Three graben zones,in en echelon arrangement,have a northeast strike.2.The developmental evolution of the Kongxi graben zone is closely related to the hydrocarbon accumulation factors.The development zone of the graben zone is located in Cangdong-Nanpi sag which is main oil sag of the study area.The underpart of the graben cut through source bed in Kong 2 member,which favored access for oil migration.The development of the graben zone controlled the deposit of the beneficial sandstone.The sandstone deposited in each graben during the same period are obviously characterized by sedimentation thickening,and distributed along the graben zone in the plane.During the development of the graben zone,the activity of the controlling-graben fault was affecting the transport of petroleum.In the low part of the graben,the source bed docked with the reservoir bed.Because of the weak activity of the fault,the petroleum mainly moved sideways,forming "side reservoir".In the higher parts of the graben zone,because of the greater fault activity,the petroleum moved upwards along the fault and formed reservoirs in the high parts of structure.3.The accumulation model of graben in the Kongxi graben zone is characterized by the "full oil and contiguous distribution" in the form.The petroleum in the graben were distributed in the longitudinal direction along the fault,and the petroleum in the transverse direction were distributed in large expanse from the lower part of the structure to the high part.The main reservoir-forming mechanism of the accumulation model of graben can be summarized in 3 points: single source bed and multiple reservoirs in graben;migration of petroleum controlled by fault;the reservoir in the lower part of structure formed by docked with source bed and the reservoir in the high part of structure formed by fault migration.