Complex Fault Block Low Permeability Of Tight Sandstone Gas Possession Of Crack Development Law Research

In our country, intrinsic fracture is growing to different extent in low-permeability tight layer. Whether the fractures exist plays an important control role on well productivity. At present, because of complicated distribution, the development effect of such hydrocarbon is poor. Especially in the east of our country fault block is small, in addition to the fractures, there are small faults for good measure, which adds the difficulty in developing oil-gas field and brings forward a new problem for development geology. On the basis of former correlation study, this paper takes Hubuzai oil field for a representative example, traverses the research approach of distribution rules and modeling in low-permeability tight sandstone layer.This paper firstly analyzes fracture cause of Hubuzai gas field, and inducts equilibrium geologic section and inclusion temperature measurement etc to describe fault in existence and check its quality, then sets up proper geologic model and structural mechanics model, and the new thought that predicts distribution probability of small fault system by structural fractal theory. On the basis of observation on cores and indoor experiment, study the qualitative and quantitative parameters by the numbers of Hubuzai gas field, provides a reference for quantitative prediction the fracture distribution. After quantitative description of fracture and evolvement history of structure, and establishment of geologic model and mechanics model, carries out quantitative prediction on the distribution of structural fracture of ES4 section by three-dimension finite element numerical simulation method. On the basis of physical simulation of structure, exertion and verification of experimental analysis, this paper studies the network characteristic of fracture seepage. It also Studies the characteristic of structural evolution and analyzes the combined mode by equilibrium geologic section method, and more predicts distribution probability of small fault system by structural fractal theory, and sets up three-dimension prediction model of fracture, prediction model of small fracture system and network model of fracture, so accurately predicts distribution rules of complex fault block and dynamic change rules of fracture formation.From above researches, some harvests are got in research theory, researchthought, and applied technology and method, summarized as "two innovations and two breakthroughs" as follows:1) On the basis of extensional tectonics theory, according to the characteristics of fracture fractal distribution, firstly conduct quantitative prediction of quantity distribution characteristics of small fracture system beyond of identification now by means of fractal geometry theory. Then present the new viewpoint that fracture seepage system of natural gas reservoir and that of medium or small fault have two channels when fluid flows through porous medium.2) This paper firstly present the new thought that appraise and research synthetically the fracture of complex fault block tight sandstone gas reservoir cooperated with four aspects such as fracture system, natural fracture seepage network system, fault system, and analysis of earth stress field applied in development.3) This paper has made breakthroughs in the research of dual-channel system, i. e. fracture system and small fault system, and the series of technologies and methods combined fracture parameters prediction and fracture seepage network system.4) Aimed at growth characteristics of multicomponent fracture, on the basis of numerical simulation on natural fracture seepage network system, conduct structural physical simulation and numerical simulation on alteration of fracture seepage system. This paper has made breakthroughs in predicting dynamic variation rules of fracture, and provides geological theory reference for pattern optimization and reconstruct, and IOR.