Potassium-rich Brine In The Middle Triassic Enrichment Model And The Prediction Of Favorable In The Southern Section Of Western Sichuan Depression

The western Sichuan Depression is one of the marine K-rich brine profitable exploration area in China, Located on top of Pingle dam structure of the Qionglai area in the southern section of western Sichuan depression Pingle 4 oil and gas exploration wells, 20 wells have received potassium-rich brine. However, on top of the same structure Fenglu 1 wells have not received K-rich brine (2008), block the potassium-rich brine of the exploration and urgent need of a breakthrough in the area.This paper made fully use of the drill core, rock wafer, well logs and seismic data to study the problems of K-rich brine exploration in Plingle area. The potassium-rich brine formation conditions and discipline were researched by remote sensing, microscope, EMP and energy spectroscopy, etc. Lineament aligned structure of the western Sichuan and Pingle area were interpreted with remote sensing technique, and used field geology survey and seismic data to certification, summarized lineament aligned structure characteristic of the study area. By observing and researching field geology section, interpreting seismic section to study structure character of brine accumulation from surface to subsurface; by rock and mineral wafer to analysis core mineral of Fenglu 1 well relation with brine reservoir layer, and with X-ray microanalysis and energy spectroscopy studied controversial potassium mineral; compared with Pingle 4 well and Fenglu 1 well with well logs, seismic data and drill core, analyzed these reservoir, scope and brine assemblages character; combined with the results of remote sensing and seismic data interpretation to analysis lineament aligned structure, accumulating brine structure, fracture system of Pingle area relation with brine reservoir, and conditions of brine migration, accumulation, conserve.Through the above analysis: Pingle dam structure is formed in the Middle Triassic anticline on top of gypsum Depression. The anticline core has great thickness of salt layers. The southeast limb of anticline develop trend northwest of thrust, the thrust is together with the trend southeast of thrust formation"y"assemblages. Rock bending and shear faults made crack development of the Leikoupo formation carbonate rock of the anticline core. That analysis, the Middle Triassic Leikoupo formation K-rich brine accumulation has seven conditions in Pingle dam structure:①Gypsum basin is the basic condition of the K-rich brine formation;②Fault is main channel of the potassium-rich brine migration;③Between the gypsum rock carbonate is good reservoir of the K-rich brine;④Fracture-hold is main accumulation scope of the potassium-rich brine migration;⑤Structural high is important site for the K-rich brine enrichment;⑥Temperature is important factor of grade level of the potassium-rich brine;⑦Great thick gypsum rock is dependable protective screen of the K-rich brine enrichment. The potassium-rich brine formation is geology, physics of the earth, geochemistry, etc, a variety of long-term result of the role of factors. Based on the K-rich brine accumulation conditions, build the potassium-rich brine enrichment mode at Pingle area. Based on the mode of the K-rich brine of Pingle area, combined with lithofacies paleography and palaeotectonics comprehensive analysis. In the western Sichuan depression divided three parts of the potassium-rich brine centers:①The center of Qinglai area;②The center of Penshan area;③The center of Hongya area. According to the accumulation mode of the K-rich brine of Pingle area and the potassium-rich center predicted four profitable exploration areas in the southern section of western Sichuan depression:①The Pingle dam profitable area;②The Gao Jiachang profitable area;③The Yan Jinggou profitable area;④The Han Wangchang profitable area. Author believes that the accumulation mode of the K-rich brine of Pingle area is very important to research the potassium-rich brine in the southern section of western Sichuan depression, and the profitable exploration area is exploration foundation of the K-rich brine of the southern section of western Sichuan depression.