Identify And Evaluation The Distribution Of Fracture In Xuer, Xinchang Area

Xinchang gas field is buildup by multiple depth of gas reservoirs. From 1989 to 1991, there are several gas reservoirs discovered in the xinchang district, include penglaizhen formation gas reservoir, qianfoya formation gas reservoir. Until October of 2000, the first exploratory well xin851 in the xuer gas reservoir of xinchang gas field had considerable prodcing, the exploration of tight gas reservoir in the 2nd member of xujiahe formation has a new start. Until now, the exploration of xinchang gas field experienced shallow to deep process, the 2nd member of xujiahe formation become the main gas producing zone. The tectonic of the xujiahe formation is well, but the physics characters are bad, the porosities and permeability of the reservoirs are very poor. The fractures are the main filtration passages and play an important role in the field. Because of this, the research about the development of fractures in the 2nd member of xujiahe formation has practice meaning for industry.Based on the research of outcrop and core, analysed the type of fractures, the density of the fractures and the validity of the fractures. In the laboratory part, observed the core from 14 wells, analysed the type, occurrence, lithology, density, length, width, filled condition of the fractures, and further, use the FMI to defined the open fractures, the half filled fractures and the full filled fractures. From the compare of identified fracture and the well log, analyse the well log characteristic of the fractures, build up a standard of identify the fractures. Contemporary, use several methods to identify the fractures,such as, distinguishing method,R/S method,probabilistic neural network. Then, compare the identification results with the fractures which were seen on the cores. Finally, On the basis of structural curvature,paleo-structural stress field simulation and structure filtering, this paper generalize the fracture development of the second member of Xujiahe formation in Xinchang area.Summarize the observation of outcrop, core and well log exploration, the fracture in the study field represent to many groups ,mainly strike direction are NEE-SWW, W-E, NE-SW, the development of nature fracture effected by the structure, lithology, depth of the formation, fault and crustal stress。Most of the fractures are low-angle fracture followed by high-angle fracture and vertical fracture,the majority of the fractures are half filled fracture, filled by calcite, part of them are filled by mud and carbon. Finally, use comprehensive evaluation Fa to evaluate the distribution of fracture on the plane, the fracture of the study area can be divided into two types: development area(Fa>0.05) and not development area (Fa<0.05)...