The Evaluation Of Chang7Shale Gas Reservoir Characteristics Of YanChang Formation In Fuxian Area, Ordos Basin

Because of the successful exploration and development of shale gas in NorthAmerican, the space of gas exploration has broadened. Compared with the NorthAmerican, China’s shale gas exploration is just beginning. Trying to using thegeological conditions of the North American, it can be found that the Yanchangformation in Fuxian area has some geological conditions to accumulation. However,the shale gas’s forming condition, the rules of distribution, and the evaluation criteria,select parameters are still need to be sure. This paper chooses the typical region tostudy, evaluate the favorable region and provide a reference for the exploration anddevelopment of the next step.Ordos basin, located at the western part of North China platform, is a large-scalesuperimposed Craton basin and a significant oil-bearing basin in China. Fuxian oilfield is on the northwest trend monocline background, it is located in the south ofOrdos basin. The study area is mainly deep lake and semi-deep lake sedimentarysubfacies; the shale is mainly developed in the bottom of long7which the distributionpresents the characteristics of thin northeast and thick southwest. the Yanchangformation has development dark sale, the thickness is10-50m and the depth is650-1200m, with good prospects for exploration.Applied with cores observation, thin section identification, pore texture analysis,SEM analysis and the X-ray diffraction, combine with the studied results of formergeologists. From the research of organic-rich shale, there is some knowledge:（1）Fuxian area’s lithology is maily laminated mud （page） of rock, laminatedsilty mud （shale）, the mineral is mainly dominated by quartz with brittlecharacteristics based on the X-ray diffraction analysis which it’s useful for the latterreservoir transform.the studied reservoir,which is a good reservoir, has the porosity of2.28%and permeability of0.4134×10^-3μm²;the types of reservoir space aredivided into grain between dissolution pores, intragranular dissolved pores,intergranular porous.（2）Kerogen type is mainly Ⅱ₁; The organic matter evolution is of amature-high mature degree. The main distribution of Robetween1.0%-1.2%, at theoil and gas coexistence stage; the southwest is higher. The total organic carboncontent is high which the average is2.618%.（3）It obtained from the comprehensive study that shale reservoirs requirementsof the study area are: total organic carbon content TOC>2%, the thermal maturityRo>1.1, the total porosity Φ>2.0%, permeability K>0.1×10^-3μm²and shale effectivethickness H>15m.（4）Combine with the s the depth situation，total organic carbon content and thepermeability of the study area, predict4favorable shale gas exploration area, the areaof ZF24-FU3-Shixian which located on the southwest are large. The NX1-ZF19-ZF20area, the NW1-ND4-NW2area and the ZF54-ZF49-ZF53area are located on thenortheast, the area is small. Compared to the measured total hydrocarbon gasabnormally high values map, it can confirm the accuracy of the results.