塔东地区褶皱构造精细分析及油气勘探方向

塔东地区存在四种褶皱构造类型:应变型主要发育于满加尔凹陷中央,劈理型主要发育于满加尔凹陷和英吉苏凹陷的斜坡部位,张裂型主要发育在阿尔金山前的塔南隆起和天山山前的塔北隆起,剪裂型主要发育于阿尔金山脉、天山山脉的山前地带。塔东地区发育有加里东—海西期、印支—燕山期以及喜马拉雅期三期构造中和面的叠加。喜马拉雅期形成的新中和面对之前的古中和面具有改造作用,它是控制油气聚集的重要界面。本区早古生代是剧烈下沉的拗拉槽,晚古生代—三叠纪是急剧抬升的古隆起,本区实际上是在残余古隆起上找油找气。古隆起的上中和面地层大多被严重剥蚀,而所残留的下中和面不是油气聚集有利区。认为有些钻井在背斜下中和面获得残留油气流,预示着相邻的向斜下中和面斜坡区构造-岩性油气藏可能成为本区的有利勘探方向。上震旦统、中—上寒武统、下奥陶统蓬莱坝组中的三套白云岩以及志留系和侏罗系碎屑岩是塔东地区的有利勘探目标。

Fine Analysis of Folds and Oil and Gas Exploration in Eastern Part of Tarim Basin

There are four types of folds in the eastern part of Tarim Basin:(1)the strain folds that commonly develop in the central part of Manjiaer Sag,(2)the cleavage folds that usually are in the slope zones of Manjiaer and Yingjisu sags,(3)the tensional folds that majorly are in Tanan Uplift of Altun Mountain foreland and Tabei Uplift of Tianshan Mountain foreland,(4)the shear crack folds that mainly develop in the forelands of the Altun Mountain and the Tianshan Mountain.Three periods of fold neutral planes are superimposed in the eastern part of Tarim Basin,which formed during the Caledonian-Hercynian,the Indosinian-Yanshanian and the Himalayan periods.The last Himalayan neutral planes are of reconstruction to former paleo-neutral planes so that they play the important roles of controlling hydrocarbon accumulation.Since this region had been a persistently subsiding aulacogen during early Paleozoic era and was a rapidly rising paleouplift during late Paleozoic to Triassic time,we are actually looking for oil and gas in the residual paleouplift.The strata of upper neutral planes are most denuded seriously in the paleouplift area while the residual strata of lower neutral planes are not favorable for hydrocarbon accumulation.The fact that relic oil and gas flows were met in some drills into the lower neutral planes of anticlines prefigures that the structural/lithologic reservoirs along the slope zones in lower neutral planes of adjacent syclines should be the hopefull prospecting locations.It is suggested that the Upper Sinian,the Middle to Lower Cambrian and the Lower Ordovician Penglaiba dolostone,as well as the Silurian and Jurassic clastic rocks are the favorable exploration targets in this rigion.