The Research On Microscopic Characteristics And Diagenesis Of Reservoir Of The Silurian And Devonian In Bachu-maigaiti Area, Tarim Basin

In recent years, The oil and gas exploration in Bachu-Maigaiti region Silurian-Devonian, It achieved gratifying results. But there are also the problem whichconstraint the study of area reservoir of weak reservoir study.On the Petroleum Geology of advanced experimental techniques basis ofobserved in thin section, scanning electron microscopy, cast thin section, x-diffractionexperiments, fluid inclusions, the conventional pressure mercury we study thepetrological characteristics of the study area, the reservoir pore types andcombinations of features, diagenetictype of action, stage of diagenesis and diageneticfacies type.The results show that Bachu-Maigaiti region Silurian Tata Elta group of cells(S1-2t) sandstone rock types are mainly feldspar quartz sandstone; Kepingtage (S1k)sandstone rock types are mainly lithic sandstone. Reservoir sandstones of DevonianDonghetang group (D3d) of the rock types are mainly quartz sandstone; keziertagegroup (D1-2k) sandstone rock types are mainly lithic quartz sandstone; compositionalmaturity of the Devonian relatively high, the Silurian is more. Their textural maturityare higher.Reservoir sand bodies in Silurian-Devonian development of the yimugantawugroup is weak, the cumulative thickness smaller Donghetang group total thickness,but is widely distributed in the study area, the rest of the target layer reservoirsandstoneswell-developed, the cumulative thickness. The main genetic types ofreservoir sand bodies in fan-delta sand body of the coastal system, the distributioncharacteristics of the reservoir sand body and thickness changes significantly affectedby syngenetic fault, paleotopography and depositionalObservation of casting thin sections and scanning electron microscopy Silurian reservoir pore types is secondary dissolution pores in the relative content of81.73%,only18.27%primary porosity, secondary dissolution pores are mainlylithicintragranular dissolved pores and dissolution, intergranular pores, the relativecontent of45.24%and35.28%respectively. Devonian reservoirs in Silurian reservoirrocks of the pore type has a greater difference of pore type primary porosity, primaryporosity content of53.51%; secondary dissolution pores in the relative content of46.49%. Primary porosity, mainly for the remaining tablets Kong, the remainingintergranular pores the percentage content of30.78%, the original intergranular porepercentage content of14.54%. Secondary dissolution pores intragranular dissolutionpores, the relative content of43.61%.Microscopic characteristics of the reservoir rocks Silurian is poor, Tata el thereservoir for the III B class reservoir; Kepingtage reservoirs is III A, class reservoir;microscopic characteristics of the Devonian reservoir better, Kirgiz TowerThereservoir of the cell group is II A, the reservoir of Donghetang is Ⅱ BSilurian reservoir rocks of clastic particles of the type of contact point-linecontact and line contact type; Devonian reservoir sandstones in detrital type of contactpoint contact, the point-line contact. Compaction of the Silurian to Devonian.Cementation is the study area, another major role in the siliceous cement in differentstrata have a certain degree of development, Donghetang group siliceous cementationdevelopment of the best, carbonate cementation is Bachu-the Markit region Anotherimportant type of cementation, its focus on development in the study area, theDevonian layers in Silurian strata development is not obvious. The clay minerals aremajor reservoirs damaging effects, but the segment at all levels is not well developed,accountable and dissolution is the formation of secondary pores in reservoirsdiagenesis.Diagenetic stage Silurian yimugantawu group,and Tata the Elta group reservoir isA_B in middle stange while Main diagenetic stage of the reservoir Kepingtage is B inmiddle stange; diagenetic stage of Devonian reservoir is A in middle diagenetic stage.Diagenetic facies types of study region: weak primary porosity and compactiondiagenetic facies, native-secondary porosity siliceous cement diagenetic facies, native-secondary porosity diagenetic facies, calcareous cementation, secondaryporosity dissolution-account of diagenetic facies, largepore dissolution diageneticfacies, dense compaction-cemented diagenetic facies. Native pore weak compactiondiagenetic facies, large pore dissolution diagenetic phase is the main role of poreexpansion, the other four diagenetic facies damaging effects of the pore. Diageneticfacies of the role of controlling factors for paleotemperature.