Comprehensive Geophysical Prospecting Method Research Of Marine Shale Gas

Shale gas is a kind of clean and efficient unconventional oil gas resource with self-generating and self-preserving. The shale gas resources in China are rich, and the distribution is wide, and the exploration prospect is considerable. At present, we have carried out the research on shale gas exploration and development, which is of great significance to ease the tension of China’s energy, and will bring direct social and economic benefits for China. The shale phase was low resistivity compared with the most of surrounding rock, and the resistivity of gas bearing can be increased, which provides a physical basis for the exploration of shale gas by electromagnetic method. This paper discusses the application of oil and gas exploration by integrated geophysical prospecting method in the jiaoshiba zone. Integrated geophysical exploration is mainly with the elastic, electrical, density and magnetic characteristics of the lithology as the basis, and research the response mechanism and characteristics of the geophysical fields (gravity, magnetic, electric, seismic) of complex reservoir, and then get the structural features of the underground reservoirs by the collected geophysical data processing, inversion and interpretation. The paper discusses the formation mechanism and Marine shale associated with pyrite, and the existence meaning."Dimension reduction approximation forward correction method" by the measured apparent resistivity curve and the theory of one dimensional forward calculation of apparent resistivity curve, fix each in turn the electrical resistivity and the thickness of the strata. The characteristics of this method is to divide underground medium into as many electrical layer and observation cycle count, and maximize reflected in the longitudinal observation data can reflect the electrical layer of the resolution. So the dimension reduction approximation correction method "is to restore the right electrical resistivity and the thickness.Magnetotelluric sounding (MT) by the Soviet union scholars A.N.T ikhonov [1] (1950) and L.C agniard [1] (1953) in the early 1950 s. By measuring the earth’s natural alternating electromagnetic field to study the formation of electrical characteristics, a geophysical prospecting method of reservoir structure. This project is used in the measuring point encryption EMAP. Is not affected by high resistance shielding, high conductivity layer distinguish ability; Lateral resolving power is stronger; Data processing and interpretation techniques mature; Great exploration depth, exploration costs low, construction is convenient;Data processing and interpretation of mature technology, etc.Long offset transient electromagnetic method (LowTEM) with long grounding wire to the underground power supply, power supply mode for bipolar square wave, the presence of power source, by measuring the attenuation characteristics of the secondary field over time to accomplish the exploration depth.Long offset transient electromagnetic method is characterized by long offset, long observation window.Different formation resistivity exploration depth information can be obtained, and a series of advantages.Complex resistivity method (CR) is a kind of electric dipole source frequency domain electromagnetic exploration method, ground excitation power supply with artificial source, measuring macro secondary field attenuation process, through the analysis of underground polarization and the relationship between the abnormal body formation resistivity morphological characteristics of diplopia, so as to achieve the burial depth, the underground abnormal polarization body size information such as the purpose. Is the only electromagnetic prospecting method that can directly indicate oil and gas reservoirs. Its main characteristic is to detect the depth of the big, the space geometry and electrical high resolution, the target response sensitivity is higher than conventional resistivity method, induced polarization parameters directly associated with oil and gas reservoirs.Focuses on three kinds of ground electrical method inversion method, the comprehensive geological, seismic and electric data, in-depth analysis of the various abnormal characteristics of the electrical section and compared with seismic profile of shale gas exploration effect.Building the underground geoelectric structure pattern of study area, predict the high gas bearing, shale gas exploration and development in the future to provide experience and guidance.