| In Junggar Basin in the south margin of Midong Lucaogou group is a very important shale formations. Through the exploration and evaluation,get a clear idea of Lucaogou group shale oil and gas resource potential,has very important significance to the development of local economy and energy. In addition,the exploration and development of shale gas in China has just started,through the investigation and evaluation of shale gas resources in continental basin,will enrich and promote development of continental basin oil shale gas resources evaluation theory. In this paper, based on previous research work, through the implementation of field geological survey route, outcrop measuring fine, fine description and sampling systems, interior identification and analysis of shale gas parameters, the integrated use of petrology, sedimentology, organic geochemistry and other research tools to study the sedimentary characteristics of the district Lucaogou group shale and shale gas organic geochemical characteristics.To sum up,the knowledge mainly includes the following several aspects:Through the systematic collection and analysis of relevant regional survey information and previous the research resultsthrough in the southern margin of the Junggar Basin,research results obtained that the study area in Junggar- Turpan ancient rift within the plate above, belonging to two structural units in North Tianshan thrust fault with the Fukang three tectonic units within it is Bogda piedmont thrust belt, the development of high-angle thrust faults. Fukang region developing faults have broken the western part of imbricate thrust faults, Gumudi fracture, miquan fracture, seven Bay fault, Shuimogou- Alexander Topol Henan fracture and fracture of the western part of the demons, both NE Trend reverse fault. Fukang Alexander fault rupture and demons controlling the north and south boundaries of the study area. Development has Gumudi anticline fold and seven Bay anticline, and near Urumqi City, a small-relief of the syncline. Sedimentary strata more complete, the oldest area of the Lower Carboniferous strata, the latest Quaternary.By outcrop observation, systematic sampling and laboratory work, study the depositional environment of the Permian region Lucaogou Formation shale facies, thickness and depth and other indicators, that the study group Permian Lucaogou shale has the following characteristics:Lucaogou Formation Lithology can be divided into three sections. Under section mainly gray and black, black mudstone, siltstone in lamellar dolomite, a small amount of limestone, sand grain development bedding and horizontal bedding. The middle is a large set of white, gray, gray-green, gray and black in the thick-bedded sandstone, siltstone and mudstone with a small number of conglomerates and dolomite, with horizontal laminae, sand grain bedding, wavy bedding and ripple marks structure. The segment is mainly gray, gray-green, gray, gray and black in thin-bedded mudstone, siltstone, sandstone, and small amounts of fine sandstone, conglomerate, dolomite, are developed trough cross-bedding, wavy bedding, sand laminae management, small liquefaction deformation structure, sequence bedding positive tablets, parallel bedding etc.Lucaogou Formation black shales containing pyrite and these mostly have fine grained pyrite coal or spherical shape, as well as a small amount of filamentous or cyclic, indicating that water was deposited genus hypoxia strong reduction saltwater environment; trace elemental analysis indicators, V /(V + Ni) ratio is much larger than the threshold value 0.46; V / Cr ratio is greater than the threshold value 2, U / Th ratio is much larger than the threshold value 0.75; organic carbon content greater than 2%. Evidence of these three areas are indicative depositional environment having reducing characteristics.East of Southern Fringe of Junggar Basin sedimentary facies along the NW-SE direction elongated distribution, from left to right shore- shallow lacustrine- deep lake- semi-deep lake- shore shallow lake, since the study area location for the Junggar Basin the southern edge of the eastern Midong scope of the study is small, the overall deposits in the basin- settlement center, deep lake- semi-deep lake phase. This facilitates reducing the formation of the environment, but also conducive to the preservation of shale diagenesis of organic matter, accumulation and transformation, but also for the stable distribution shale deposits provide a good environment.The total thickness of the shale in the study area is between 697 ~ 851 m, 600 m above the overall thickness from northeast to southwest direction gradually thickened, the thickest position is Yushugou position(851m), the thickness of the thinnest in Lucaogou(697m), near Urumqi small syncline within shale continuous distribution, stable thickness. Eastern shale thickness meter lofty standard of 15 meters, which provide good conditions for horizontal drilling and staged fracturing, also has enough organic matter and ample reservoir space for the study area to provide a guarantee.Objective layer depth study area has the following characteristics: From between Urumqi to Lucaogou is a relatively wide gentle syncline syncline within no major fault influence on Lucaogou group overburden Permian Hongyanchi group, Triassic warehouse base and Xiaoquangou ditch. After a large cross-section measurement system, calculated on Syncline Lucaogou group cumulative thickness of overlying strata in between 1320 ~ 1850 m, moderate burial depth, is conducive to the preservation and development of shale oil and gas; syncline east of Lu after grass ditch, Dadonggou and Sangonghe, the three areas under the control groove, faults, folds well developed, very large dip, strata separated by very fragmented target layer depth change is very large, is not conducive to shale gas Tibetan formation.Overall, the southern margin of the Junggar Basin Midong Lucaogou source rocks high abundance of organic matter, the overall evaluation was good hydrocarbon source rocks. TOC average of more than 5%, far more than the shale gas producing organic carbon content of 2% minimum standard, good quality kerogen. Laterally from left to right, Midong Lucaogou organic carbon content(TOC) mean increases from 4.12% to 6.10%, regularity is obvious, perhaps due to the water Sangonghe direction gradually deepened, reducing environment stronger, better preservation of organic matter and other causes. Under Lucaogou group, middle, upper segment, the overall evaluation was good hydrocarbon source rocks. TOC content is preferably in the middle, followed by the next segment, the segment worst kerogen quality is generally very good.Overall Midong Lucaogou Formation shale, sapropel group and chitin group content is rich, reflecting the better the oil generating potential; vitrinite also have a general content, which represents a certain amount higher plants parent material input, may be in situ aquatic higher plants, it may be a heterologous land input; inertinite outstanding content in some samples, other content in general, to a certain extent, this interval indicates poor organic matter, the degree of oxidation higher. The study area kerogen from Ⅱ1, Ⅱ2, Ⅲ kerogen are distributed, type Ⅱ kerogen accounts for the main part, followed Ⅲ type. The upper segment is mainly Ⅱ2 kerogen, compare to 60% of its share of the total sample for this segment, followed Ⅱ1 and Ⅲ kerogen, Ⅱ1 and Ⅲ kerogen 20 percent each; no test is successful middle sample; the lower section of Ⅱ2, Ⅲ kerogen, the proportion was 50%. By atomic ratio and MACERALS division kerogen type, the area to type Ⅱ kerogen,Ⅰtype supplement.Study area Lucaogou group organic matter in black shale in vitrinite reflectance(Ro) is between 0.62%- 1.19%, the sample is 26, the average was 0.79%, in the thermally mature stage, oil generation as Lord, may be a good shale oil development area. In such a mature stage of hydrocarbon source rock, a small quantity of heavy hydrocarbon gases, methane substantially no, not very good shale gas source rock. Longitudinally from shallow to deep, reach maturity value(Ro> 0.70%) of the sample have tended to increase. |
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