奥陶系碳酸盐岩是塔中地区油气勘探的重要目的层。本文在讨论塔中地区奥陶纪区域构造背景和奥陶系岩性段划分的基础上，建立了塔中地区奥陶系构造－沉积模式，并用三维有限元数值模拟方法对塔中地区有利碳酸盐岩裂缝储层发育区进行了预测，以期指导塔中地区碳酸盐岩的油气勘探。%Ordovician carbonate rock formation is an important target for oil and gas exploration. In this paper, on thebasis of regional structure backgrounds , Ordovician lithologic intervals are divided in Tazhong area and, structural- depositional model is built up. With the help of three dimension finite element simulation method, the favorableareas of carbonate fracture reservoirs are predicted. The purpose of this paper is to give a direction for carbonate oiland gas exploration in Tazhong area. Conclusions could be summed up as follows: (1) The lithologic characters ofmiddle - upper Ordovician in the major part of Ordovician uplift in Tazhong are dramatically different from that ofadjacent slope, especially from that of slope of south Manjiaer depression in the north of Tazhong number onefault. The lithology of Ordovician in the major part of Tazhong uplift is dominated by carbonate rocks, and thelithology of middle - upper Ordovician is mainly sandy mudstone in the slope of south Manjiaer in the north ofTazhong number one fault. (2) Sedimentation during Ordovician in Tazbong area is controlled by intracratonic de-pression and Cratonic margin aulacogen, which are with different properties of prototype basin. The uplift and sagin intracratonic depression have prominent control to the sedimentation of Ordovician. Middle - upper Ordoviciandeposition in the major part of Tazhong uplift is controlled by the large scale anticline in the intracratonic depressionformedn early Caledonian (the end of early Ordovician). The restrained platform facies are developed in shallowwater in such places where platform clinoform, platform margin, semi - restrained platform (include platform flat,lagoon) and Carbonate morphologic units are found. The northeast boundary of Tazhong area is sharp margin con-trolled by the early movement of normal fault of Tazhong number one fault. The sedimentation of south Manjiaerdepression in north Tazhong is controlled by Kuluketage- Manjiaer aulacogen, the sediments are clastic rocks withslope and deep water basin facies. Middle - upper Ordovician deposition of Tanguzibasi area in south Tazhong iscontrolled by the syncline of intracratonic depression, the sediments consist of clastic and carbonate rocks withdeeper open platform facies. Lower Ordovician in Tazhong area is platform facies controlled by the intracratonic de-pression, and the structure - sedimentation is no apparent difference between the major part of uplift and adjacentareas. (3) The first favorable fracture zones of Ordovician carbonate reservoirs being predicted in the major part ofTazhong uplift include the following areas: Tz161 - Tz44 area, Tz24 - Tz26 - Tz27 area, Tz45 area, Tz3 area,Tz52 area, Tz403 area, Tz2 area, Tz22 area, the east part of Tz35 area, the west part of number one fault and soon. Correlation the results predicted with the observations of core fractures and well logging evaluating, the fitnessis about over sixty- six percent. So it is proposed that three dimension finite element simulation method is very ef-ficient in predicting carbonate fracture zone.
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