Developing Features And Growth Mechanism Of Fractures In West Xingqi Areas Of Daqing Oilfield

The Xingshugang development areas in Daqing Oilfield were of sophisticated structures and numerous distributed faults. It was formerly regarded that Putaohua layers in North Xingshugang areas were epigenetic faults. However, it was discovered by fine contrast in west Xingqi area that the zone thickness on both sides of PI faults differed. It could be prelimilarily concluded that they were contemporaneous faults. In order to figure out the fault properties, main fault developing zones and the relationship between faults and sand body distribution, researches were carried out on the developing features and growth mechanism of fractures in west Xingqi areas.On the basis of relevant domestic and overseas documents and findings, studies were carried out according to the actual situations in north Xingshugang areas. Firstly, Faults of Putaohua zones in west Xingqi areas were accurately interpretted, so as to analyze their evolution history and developing mechanism.Then, fracture systems were divided. In this method, layers could be precisely contrasted, the control of faults over sand bodies could be analyzed, and fault controlling models over sand bodies were established. Ultimately, a new technology for layer contrasts in contemporaneous fault sedimentation was set up, which laid a solid foundation for the analysis of remaining oil in contemporaneous faults.The new technology was the innovation of this article. Periods of active fractures were identified through their growth and evolution history. Layer subdivision was carried out in vertical sedimentary time sequence, in order to figure out changes of zone thickness formerly considered by ancient topographic differences. On the principle of "even up", the zone thickness difference was reallocated to the lowest of PI322unit. Features and exact growth locations of faults were recognized, thickened parts of thrown walls were averagely reallocated to exact growth locations. Thus, new recognition of fine layer contrast was formed. The new method could be applied to the central, eastern parts of Xingqi areas and all the zones of contemporaneous faults, and provided solid geological foundations for dynamic analysis of oil layers, analysis of remaining oil, further extraction, adjustment and reformation of oilfields. And it was of significant importance in the fine further development of thick oil layers in old oilfields.