| Based on the exploration and research of Sichuan basin, I know the reservoir of Xujiaheformation in Sichuan northeast possess favorable exploratory potentiality, particularly the Yuanbaarea have been the focal area of natural gas increased. But since the explored level is lowrelatively, the gas concentrated rule and the master controlling element with reservoirdevelopment of Xujiahe formation of this area are not clear. So this article utilizes considerablefundamental researches, which include individual well analysis, sedimentary facies, electrofacies,seismic facies etc. It establish the sedimentation model of Xujiahe formation of this area.Meanwhile the article have researched neogenic basic quiescent element of gas reservoir of tightsand and dynamic neogenic process of Xujiahe formation of Upper Triassic in Sichuan northeastby abundant testing data, reserching measure between geology and physics of the Earth:(1) thedistribution, generation, evolution and comprehensive evaluation of rock which generateshydrocarbon.(2) reservoir feature, sedimentary feature, diagenesis, honeycombed evolutionaryrelationship, developed distributive rule of reservoir and master controlled element researched.(3)researching the movement and accumulation, preservative condition and structural evolutionalaffection to reservoir.(4) comprehensive forecast to reservoir, objective evaluation and optimize.It has acquired following main research outcome and aware innovation.The hydrocarbon source rock of Xujiahe formation in Yuanba area Sichuan basin has thefeatures of multi-set, multi-layer, complete-coverage, thin-single layer, accumulative-totalthickness, which present the shape characters as sandwich or multilayer-cake; the totalthickness of source rock is120-300m, and gradually becoming thicker from the northeast to thesouthwest; the Source rocks is mainly consisted by Ⅱ1/Ⅱ2type-based and Ro ranged between1.58%-2.38%, organic matters are in the high maturity stage and gas-generating dominantly.Calculation natural gas resources in Xujiahe formation of Yuanba-Tongnanba area in NortheastSichuan total of7325billion party, and have good resource potential; The hydrocarbon source,reservoir condition of the Xujiahe formation in Yuanba area is superior and source-reservoir is"sandwich" type structure, and has condition good of transport and storage. one hundred billionparty form scale of large compacted sandstone gas field is expected to exceed at the secondsection of Xujiahe formation in Northwest Yuanba area is first put forward.The reservoir rock type of Xujiahe formation in Sichuan basin Yuanba area is mainlyfeldspar lithic sandstone, lithic sandstone, debris quartz sandstone,etc; Reservoir space type is mainly between grains solution pores, and in grains solution pores and grain of the hole, whichwas low porosity and permeability and tight; Sedimentary microfacies is the key factor to controlthe reservoir development of Xujiahe formation of Yuanba area is first put forward. The highquality reservoir was mainly developed in high energy zone such as underwater distributarychannel and mouth bar, and established the sedimentary model and development mode ofobjective reservoir of Xujiahe formation in Yuanba area; Reservoir of Xujiahe formation hadburied by complex diagenetic process of compaction, cementation, dissolved, pressure anddissolve, and compaction and cementation is a major factor lead to reservoir compaction whiledissolution is a key factor in the formation of high-quality reservoir. Predict the distribution of themain reservoir plane by using integration of comprehensive study of geology and seismicinversion results.Sandstone reservoir of the second section of Xujiahe formation in northwest Yuanba area hascharacteristics of deep buried (4000-5000m), good physical character(Porosity:5%-12%andaverage7%), great thickness(40-100m), wide distribution(＞500Km2), has formed the basisgeological conditions of large gas field; Therefore,it is confirmed that the continental clasticreservoirs in the deep burial, strong compaction background has still exist relatively goodsecondary porosity zone. The super-deep and large phased-type porous tight sandstone gasreservoirs is the main aim of explor large and medium-sized gas fields at northeast SichuanYuanba area, furthermore the middle-shallow strata in west Sichuan depression,which hasimportant guiding significance for exploration terrestrial clastic rock of Sichuan basinThe Xujiahe formation in Northeast Sichuan develop constructive-lithologic gas reservoir、lithologic gas reservoir、 constructive gas reservoir and lithologic-constructive gas reservoir etc.The gas reservoir of the second and forth section of Xujiahe formation in Malubei area islithologic-constructive. Also the reservoir of the forth section of Xujiahe formation in Yuanbaarea is. The reservoir of the second section of Xujiahe formation in Yuanba area is bull lithologicgas reservoir. Among these, lithologic gas reservoir and lithologic-constructive gas reservoir arethe main types of gas reservoir, which belong to unconventional tight gas resources of sandstone；the controlling factors of tight gas resources of Xujiahe formation in northeast Sichuan include:①Good source rocks are the material basis for natural gas gathering the accumulation;②Reservoirquality is the key to gas accumulation;③The superimpose of ancient and modern structuresonplays significant role in the control of accumulation and distribution of reservoir;④Thetransformation of late diagenesis, especially the development of cracks controls high productivityof oil and gas.According to the hydrocarbon source rock comparison, gas reservoir tracing, transformingsystem and relationship between hydrocarbon source rock and reservoir allocation, migratorydriving force etc. Gas migration and accumulation mode of Xujiahe formation of Upper Triassic inYuanba area was established. The Xujiahe formation in northeast Sichuan is mainly withnear-source play, with sand as the main carrier, forming a wide review of natural gas accumulationzone; Individual gas reservoir fractured, makes natural gas vertical dispersion, forming gaseffusion area, and secondary gas reservoir in overlying formation. Different gas filling in palymodes were established: migratory driving force in distal play is mainly buoyancy and the way ofgas filling is buoyancy force; The migratory driving force of gas in near-source paly is mainlyexcess pressure difference from source save. The gas filling is mainly in prior of tight reservoir.The reservoir fine and close is the major factor of gas reservoir normal high pressure. The gas filling manner basically is continued producing hydrocarbon, everlasting filling.Through the above research, we can further identify that the Xujiahe formation of Yuanbaarea in Sichuan Basin possesses a well background of resources, and simultaneously developedseveral sets, multiple types of reservoir. A lot of trap types are coexisting. The migration,aggregation, and preservation condition of the oil and gas are advantageous. All these contribute tothe accumulation of oil and gas reservoir. From allocate situation of gas developing to reservoirpointing of view, The Xujiahe formation in Northeast Sichuan possessed the basic conditions oflarge-medium gas field formation. On this basis, to restore the formation process of tight gasreservoir of sandstone of Xujiahe formation of Upper Triassic in Northeast Sichuan. And throughthe anatomy of a typical gas pool, sum up the controlling factors of gas concentrating of tight gasreservoir of sandstone of Xujiahe formation and initially identify the formation mechanism oftight gas reservoir of sandstone of Xujiahe formation. Furthermore with three stage method ofcontrolling facies technology, comprehensively predict the distribution range of chief reservoir ofXujiahe formation, based on which, pick bull unconventional tight gas reservoir of sandstone inNorthwest as advantageous exploration target, indicating the exploratory direction of tightsandstone of Xujiahe formation and other nonmarine layer system in Northeast Sichuan, andgreatly improving exploration efficiency. |
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