Geological-Geochemical Characteristicsand Accumulation Analysis Of Jurassic Oil Sands In The Tarim Basin

Oil sands as an unconventional resource, which is a huge amount of resources, acting as a major role in the world energy structure. Chinese oil sand resources are very rich, but oil sands geological study started late, so oil sands resource is potential. In 2006 a new round of petroleum resources assessment shows the basic identification of the Tarim Basin oil sands surface exposed, the preliminary calculation of the amount of geological resources of oil sands basin size of 12.36 × 108 t. But the overall level of exploration is low, studiesfor oil sands geological characteristics and distribution and accumulation does not in-depth. This article will study oil sands in Bashijiqike area Kuqa Depression, hoping to provide reference for the exploration and development of oil sands in region and the whole basin.Through field geological survey of oil sands and oil sands drilling in Bashijiqike area,we can discover rich oil sands resources in Bashijiqike area, and the Jurassic oil sands belong to the Kezilenuer formation(J2kz). In the field we can see that the Kezilenuer formation oil sands is a total of three layers and oil sands cumulative thickness is about 7m.Through field measured sections, we can see the oil sands as 2 layers with a total thickness of about 7.5m. High-quality oil sands core length of 9.27 meters as 3 layers in Ba Oil Sands 1 Drilling.By rock flakes, particle size analysis, cast sheet, scanning electron microscopy, x diffraction analysis,porosity and permeability and oil content test of theKezilenuerformation formation(J2kz) oil sand in Bashijiqike area,it shows that kinds of lithology are mainly lithic sandstone and pebbly coarse sandstone, and sandstone, siltstone and mudstone development less. The main mineral components to debris, compositional maturity is low. Combined with previous data, field characteristics and comprehensive experimental analysis, reservoir rock samples reflect the sedimentary facies are meandering river bed subfacies phase.Overall oil sands reservoir rock porosity is a low- medium, and the permeability is unevenly distributed.Special low permeability, low permeability, the permeability and permeability oil sand reservoir section are distributed, but non-reservoir rocks are low permeability. Oil sands reservoir oil content between 2 and 5.28%, the average of 3.64%. Reservoir rocks are developed primary porosity and secondary porosity,primary porosity is divided into primary intergranular pores and primary intergranular bore,secondary porosity is divided into secondary intergranular pore, secondary grain bore hole and molds. In addition to mold pore and fracture are also well developed. The image statistics show that secondary intergranular porosity is the main hole on the number and area. The average faces rate was 7.73%, the average median was 1.47, an average pore diameter was 352.32μm, the average pore-throat ratio was 7.42, throat width distributed between 1.3~56.76μm, the average was 6.87μm. Diagenesis types of oil Sand Rock in Bashijiqike area are compaction, pressure solution, cementation and dissolution.The strong compaction is the main reasons that the porosity and permeability of the Kezilenuer formation(J2kz) oil sand reservoir in Bashijiqike area decrease, one of the destructive diagenesis. Dissolution is important diagenesis types in the study area.Dissolution promote the formation of secondary porosity and development of effective reservoir. Siliceous cementation development of the Kezilenuer formation(J2kz) oil sand reservoir is more common, mainly as quartz overgrowths. Oil sands of the Kezilenuer formation(J2kz) due to degradation strongly,the main ingredient to asphaltenes and saturated hydrocarbon content is about 15% on average. Bacteria contribute organic matter greater than algae,Source rocks have characteristics more terrestrial organic matter. evolution stages of oil sands extract organic is in advanced stages. Widely distributed semi-deep lake- deep lake Phase dark shales of the Kezilenuer formation(J2kz) and the Cakmak formation(J2q)may be important hydrocarbon source rock section.Considering the regional source rocks, oil sands reservoirs and tectonic activity characteristic, regional power is a necessary condition in the area of oil and gas accumulation.Since intracontinental subduction and from north and south of regional compression, Kuqa depression formed in a number of north-dipping thrust faults which formed a good hydrocarbon migration pathway. Oil migrated along the fault continues into or near the surface in communication with the atmosphere, subjected to washed with water and a biodegradable to form the oil sands.