Marine Oil And Gas Preservation Conditions Comprehensive Analysis, Jinsha-renhuai And Its Adjacent Areas

The study area subjects in the North of Central Guizhou uplift and Qianbei depression, located in Jinsha-Renhuai and its adjacent regions. After decades of work on the lower Palaeozoic marine oil and gas reservoirs exploration, has made a little progress. Although the district with excellently condition of Hydrocarbon source rocks and reservoirs, however, due to experience more of tectonic activities, resulting in a complex geological structures, faults are well developed in the region. The led to Greater impact on hydrocarbon reservoirs saves. Therefore, to strengthen the research of the oil and gas preservation conditions for oil and gas exploration in the area of is crucial. Papers based on the field investigation of preservation conditions of oil and gas, in conjunction with petro logical, mineralogical and isotopic geochemistry of analysis, system research the characteristics of cover rocks, faults and its seal, hydro geological characteristics. On the basis of analysis, uses fuzzy mathematics comprehensive evaluation method optimizing the favorable oil and gas preservation block and semi-quantitative assessment, in order to provide a reference for future oil and gas exploration in the region. Yielded the following results:1. Field surveys on the mudstone cap rock of the Qiandong system and lower Silurian Long maxi Group, carried out a detailed classification. Cap rock of Qiandong system is mainly composed of: carbonaceous shale, siliceous rock, clot rock and silty shale. Cap rock of Long maxi Group is primarily composed of: black carbonaceous Shale, calcareous mudstone, shale, limestone, Sandy(Sandy) shale.2.Analysis the sedimentary facies of the Niutitang and Long maxi group.The sedimentary facies of Niutitang is deep water shelf and shallow water shelf, the plane was north east trending; The Long maxi`s facies is deep water shelf-the shallow water shelf and diamictite shelf facies,in sectional. Dominated by Qian zhong uplift effect control, from south to north was, in order, the tidal flat-diamictite shelf-the shallow water shelf phase.3. Use x-ray diffraction analysis of whole-rock and clay minerals to analysis of the mudstone cap rock of Niutitang and Long maxi Group. Analysis results showed that both were dominated by quartz and clay minerals. Most of the illite content is more than 50%. Petrological characteristics of brittle minerals causing brittleness both large and vulnerable to the effects of tectonic activity fracture more easily, which is not conducive to preservation.4. Material analysis showed: Niutitang argillaceous rocks has better cover ability with high densification and strong sealing ability, belongs to Ⅰ class quality cap, t is very important to Denying group of oil and gas reservoirs; Long maxi group shale cap belonging to the closure of the better class Ⅱ cap, but due to the construction factors, only as a partial cap.5. Combination of hydrocarbon source rock and hydrocarbon-generating history on Dingshan1 well of Cambrian gypsum rocks cover the effectiveness of the initial analysis. Results showed that gypsum rock sealing with excellent ability of physical properties, Unable to form an effective seal of oil and gas formation dues to hydrocarbon traps in history and time do not match. Therefore for the cover layer, the future emphasis should be put on hydrocarbon generation history of study on relationship between coupling and traps.6. Research on the sealing ability of the secondary fracture, Zunyi-Hezhang fault. System collected fillings and matching surrounding rock samples c, o and Sr isotopes on samples and analyses of fluid inclusions. Isotope analysis showed: in a weaker difference between surrounding rock and fillings, the fluid mainly comes from the surrounding rock. Fluid inclusions in the gas phase, and only a small amount of inclusions in liquid phase; gas phase dominated by organic matter, liquid portion is mainly water; inclusions are based on temperature 166.6℃~302.4℃. Permian Basin hydrocarbon-generating history shows that fluids. Highlight lower Paleozoic of the secondary fault sealing good.7. According to the distribution of hot springs and hot springs temperature estimation of the atmospheric water recycle depth of penetration. According to the distribution characteristics of fault sand genetic model about spring showed that the meteoric water infiltration depth associated with fractures; in the area of effect stratum with high degree of opening. Combined drilling practices show that regional hydro geological characteristics of lower Paleozoic marine strata in overall poor performance, but there still exist of good hydro geological conditions, in local.8. Systematic analysis of regional characteristics of cover rocks and sealing ability, fault seal and hydro-geological characteristics then division of two oil and gas preservation favorable area: Chongxing town blocks and Gulin-xishui blocks. Using fuzzy mathematics comprehensive evaluation method on 11 factors affecting preservation conditions in the region were analyzed and evaluated, the evaluation results show that town blocks preservation conditions better than the Gulin-xishui block again.