The Research Of Conditions For Hydrocarbon Accumulation Of Kongdian Formation In Huimin Depression

There are abundant hydrocarbon resources in Huimin depression. The proven reserves mainly concentrate in the middle and shallow zone at present. Research degree is low in the deep zone. In order to maintain the stable development, it is necessary to seek the advantageous exploration target area in the deep zone. The paper takes the prototype basin research of Kongdian formation as the foundation in Huimin depression and analyzes the control action to evolvement of basin in the structure transition period. The deposition system is researched and depositional model is established. The diagenesis and the reservoir quality are researched based on the geologic analysis datum. The conditions for hydrocarbon accumulation are researched based on the petroleum geology analysis. The advantageous exploration target is found in Kongdian formation finally.The paper establishes the framework of the deep zone in Huimin depression with the sequence stratigraphy viewpoint and analyzes the fault activity speed of the main fault in the depression. It is thought that the sediment of Kongdian formation is controlled by Xiakou fault, Ningnan fault and Wunan fault. The Xiakou fault is the master control fault in the south of Huimin depression. The lithosomic body of Kongdian formation is wedge-shaped body between Xiakou fault and the basin margin in the north of the Huimin depression. There is a thin layer deposition between Xiakou fault and Qihe fault. The depocenter of Kongdian formation is located the north of Xiakou fault and the north of Linfanjia area. There are terminal fan deposition and braided delta deposition in Huimin depression during the Kongdian formation period. The terminal fan deposition is the main sediment system in the basin. The braided delta system is located the south of Linfanjia area.The lithological characteristics, characteristics of diagenesis and reservoir quality are researched based on the thin slice, the body of casting thin slice, scan the electron microscope, the cathode luminescence, the electron probe and so on. The reservoir of the second member of Kongdian formation is on the stage B period of the middle diagenetic stage. The compaction function and the cementation are intense in the sandstone. There is a little pore space and the pore throat structure is very bad in the sandstone. The quality of the reservoir is bad. The hierarchy of main reservoir of the second member of Kongdian formation is IV. The reservoir of the first member of Kongdian is on the stage A period of the middle diagenetic stage. The compaction function and the cementation are intense. The corrosion function is strong in the zone that there is lots of fault. The quality of the reservoir is better than the former. The hierarchy of main reservoir of the first member of Kongdian formation isâ…¢. There is different response to different sandstone unit in Kongdian formation. Different diagenetic facies form in the different sandstone unit. The sandstone units controlled by different diagenetic facies form the diagenetic trap if they combine with certain rule.The hydrocarbon source rocks of the second member of Kongdian formation is on the high mature stage based on the geochemical datum. The reservoir of Kongdian formation is compaction and the scale of reservoir is great. The gases from the second member of Kongdian formation migrate into the tight sand; form the compact sandstone gas pool. This kind of gas pool has the characteristic of deep basin gas. The hydrocarbon from Linnan sag can migrate into the reservoir of Kongdian formation in the central upheaval zone. The advantageous area is predicted based on kinds of conditions for hydrocarbon accumulation and a definitude direction is given to oil-gas exploration.