Petrological Characteristics And Provenance Analysis Of Sandstones Of Yanchang Formation In Changqing Area, Ordos Basin

The Ordos Basin is China’s largest oil and gas basins, four sets of the explorationand development petroleum system in the basin are formation lithology hiddenreservoir, which the Yanchang formation in Upper Triassic is not only China’scontinental Triassic strata which is the earliest development of a complete layerprofile been studied, also a basin the earliest formation of oil and gas been discoveried,it plays an important role in oil exploration, and has been the main purpose of layer ofoil and gas exploration. The research in Triassic Formation in the Ordos Basin beganin the1970s, more than three decades, the Company “PetroChina of Changqing” inthe field have done a lot of work and has reached a very high level, and hasaccumulated a rich research experience in this field.The predecessors has a preliminary understanding of the southwest edge of theOrdos Basin, the6, length8sets during the deposition of paleocurrent and provenancecharacteristics, depositional systems and sedimentary facies and their spatialdistribution law, planar distribution of sand bodies and the size of the sand body. Theythink there is two provenances, northeast and southwest direction, in the period ofYanchang Formation in Ordos Basin, but the specific parent rock characteristics andsedimentary systems in two provenances, the specific content in recent years, is rarelypublicly reported. To this end, we selected the6th Yanchang Formation of Huaqingarea of the Ordos basin to do thecorresponding study, the main study is aroud thereservoir sandstone rocks and other features to explore further investigation and todetermine ancient flow characteristics of the study area and the source direction andsource features, in-depth understanding the types of sedimentary facies of Chang6, its development and distribution characteristics, we expect that these results can providean important basis for looking for more high-quality reservoirs to speed up the pace ofexploration and development of the ChangQing area and the expansion of explorationresults.In this study, detailed core observation and description, cast thin section,cathodoluminescence, scanning electron microscopy and X-ray diffraction analysis onthe basis of the existing research results combined with regional geologicalbackground and previous system of the Chang6reservoir sandstone rockcharacteristics in the Huaqing area, Ordos Basin; then based on the sandstone rocktypes, different type of fabric samples of heavy mineral analysis, lithological analysis,maturity analysis of biological and bio-analysis, phase-type system analysis;and traceelement analysis, the constant element analysis, isotope analysis, to do the long6Formation source analysis in Huaqing, Ordos Basin.Combined with light mineral assemblages of the study area, rock structureparameter characteristics, and characteristics of heavy minerals we found in the studyarea there are two material sources, the northeastern and southern provenance.