Evaluation Of Hydrocarbon Source Rock In Upper Paleozoic, Yanchang Gas Area

Erdos Basin experienced within mainland multistage orogeny and basin formation, inner craton formation from Late Carboniferous to Triassic. Extended gas area is located in the east of Erdos Basin, is the inadequate exploration potential region currently. The main sedimentary type is Shore-shallow lake in Neopaleozoic, suitable for sedimentary and save of hydrocarbon source rock. In the study area, hydrocarbon source rock distribute stability in a wide range, mainly for coal, dark mudstone.This study attempts to describe the sedimentary distribution, character of hydrocarbon source rock, which apply the concept of sedimentary organic facied, to deepen the understanding of Upper Paleozoic source rocks. Carry out the search and evaluation work for the hydrocarbon source rock. Clear out the resource distribution and potential, guiding the next exploration and development work. For Upper Paleozoic source rocks of Yanchang gas area, samples will do some tese including organic petrology, geochemistry analysis test. kerogen microscopic examination, rock pyrolysis, vitrinite reflectance, organic carbon, element analysis, GC-MS combination. Draw the following main conclusions:1. Through the study of available literature and information, the upper Paleozoic identified in shore-shallow lake subfacies, this sedimentary subfacies appear in above of Shanxi group; Followed by the lagoon subfacies and open platform facies, appearing in Benxi group and Taiyuan group. The GC-MS features also confirms the deposition distribution environment of hydrocarbon source rock.2. The best extended gas source rock in the upper Paleozoic is Shanxi group of Yanchang gas area.It’s characteristics are large thickness, stable distributon, high abundance of organic matter and good types. At the same time, organic matter in the maturity and over mature stages. Especially, the good hydrocarbon source rock is the coal seam. The mainly production of hydrocarbon source rock is gas. And it followed by Taiyuan formation source rock, which hydrocarbon potential generation was limited.3. Comprehensive classification of sedimentary organic facies were combined structure, sedimentary, petrology and geochemistry. The Benxi group is dicided into the overing water herb (swamp); The Taiyuan group is divided into the open lacustrine basin algae matter phase; Shanxi group, Shihezi group and Shiqianfeng group are divided into different residual yield(floating bog) organic phase. At the same time, Yanan area is the development area for hydrocarbon source rock. The delta front subfacies of Yanchang gas area is the secondly potential area.4. Sedimentary organic facies was only qualitative divided by organic petrology and organic geochemistry. The transitional data cannot be well divided. In the use of partition scheme, index selection should combined with the actual situation, considering the thermal evolution influence factors simultaneously. The next working key is quantitative study on sedimentary organic facies.