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The Study Of Sedimentary Facies And Reservoir Of Neopaleozoic In Daniudi Gas Field

Posted on:2011-04-06Degree:DoctorType:Dissertation
Country:ChinaCandidate:C X TanFull Text:PDF
GTID:1220330368989043Subject:Mineral prospecting and exploration
Abstract/Summary:PDF Full Text Request
Ordos Basin is the second largest inland sedimentary basin with prolific in oil and gas resources in China. In recent year, demonstrated reserves of Neopaleozoic in many gas fields indicated that the Neopaleozoic reservoir of Ordos Basin will likely continue to yield additional gas discoveries for many years to come, the expansion and exploitation of Neopaleozoic reservoir have great practical and economic significance to the sustainable development of the recent gas-oil industry in China.Daniudi gas field lies on northeast part of Yishan Slope in Ordos Basin, and the primary oil-bearing bed is Carboniferous Taiyuan Formation, Permian Shanxi Formation and Xiashihezi Formation. It is implied that there is great potentiality for exploration in the future. However, the understanding of the hydrocarbon concentrated regularity of Neopaleozoic reservoir in Daniudi gas field was not deepened due to the relative complexity of sedimentary environment, characteristics of reservoirs and the master controlling factors of gas concentration, a momentous breakthrough in highperformance exploration and exploitation of gas reservoir has been influenced in past years. In allusion to those issues about Neopaleozoic reservoir in Daniudi gas field, many systemic researches that include sedimentary facies, microcharacteristics of sandstone reservoirs and hydrocarbon concentrated regularity have been carried out by means of many branches of learning theory system and testing measures.Based on analyzing mineralogical component of sandstone, light minerals, heavy minerals, genetic types of quartz cathodeluminescence, REE characteristics, it is suggested that sedimentary source in this area originate from the northern part of Ordos Basin in the period of Neopaleozoic Formation, and controlled by the northeast provenance obviously. In addition, it is indicated that the parent rocks are derived from metamorphic rock of Precambrian succession in the ancient land of Yin Mount at the northeast side of Ordos basin. Based on source direction, sedimentary characteristics and studying in the fields, rivage epeiric sea- braided channel delta-river deposition system are identified, of which barrier bar microfacies in Taiyuan Formation, distributary channel microfacies in Shanxi Formation and channel bar microfacies in Xiashihezi Formation are framework facies of gas reservoir and controlled the distribution of sand bodies and accumulation of gas.It was shown that the sandstones of Xiashihezi Formation and Shanxi Formation are medium to coarse lithic sandstone and lithic quartzose sandstone, the sandstones of Taiyuan Formation is quartzose sandstone. The content of mud matrix is low and the type of cements observed are quartz overgrowths, carbonate and clay minerals which including kaolinite, illite and chlorite. The main clastic particles constituents observed in sandstones are moderate to fine in separation, sub-angular and sub-rounded in psephicity, and the grains mainly have line-point contact, line contact taking second place, particle supported, porosity typed cementation. It was also revealed that the main types of pores are remnant intergranular pores and dissolved pores, the foremost type of pore assemble is intergranular pore-dissolved pore type, and the pore configurations are middle Pcd-coarse pore throat and middle Pcd-fine pore throat. Every reservoir exhibits great difference in physical property, and its interlamination, intraformation and plane shows relatively intensive heterogeneity. The quality of He2 sandstone reservoirs is the best and Tai2 is the second, He3 and Tai1 are better than the rest. Taken as a whole, they are the typical low- ultra low porosity and permeable reservoirs. The physical property is controlled by sedimentation and diagenesis.It is revealed that the diagenesis of the Neopaleozoic sandstones reservoir are in the early diagenesis phase B to late diagenesis phase A while part of the reservoir is in late diagenesis phase B. The diagenesis of the sandstones mainly include compaction, cementation and dissolution. The compaction and cementation destructed lots of pores of Taiyuan-Xiashihezi reservoirs intensively, but dissolution altered the hole structure effectively, at last the reservoirs quality has been improved. Integrated researches including sedimentary facies and reservoir characteristics with actual situation in this area, the sandstone reservoirs could be divided into 4 types.Ⅰ-good reservoirs andⅡ-appreciably good reservoirs varying degrees developed in every reservoir, especially in He2, He1, Shan2 members,Ⅲ-middle reservoirs is occured in the part of Shanl and Tail members,Ⅳ-poor reservoirs is occured in the part of Tai2 member.Based on the research of the geological conditions for gas enrichment, deposition, diagenesis and part tectogenesis are the main factors of controlling the enrichment and distribution of hydrocarbon. According to the range of deliverability, it is certain that He3, Shan2, Tai2 members are the main producing pay of study area, and some advantageous blocks of gas are predicted of Taiyuan, Shanxi and Xiashihezi Formations in Daniudi gas field, which provide the credibility geology reference for perspective exploration and exploitation in this area.
Keywords/Search Tags:sedimentary facies, reservoir microcharacteristics, diagenesis, reservoir physical property, hydrocarbon enrichment rule, Neopaleozoic, Daniudi gas field
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