Analysis Of Sequence Stratigraphy And Its Controlling Factors To Reservoir In Ordovician In Tazhong Area, Tarim Basin

Tazhong area is an important oil and gas trap in the west of China. Recently,exploration and inspection have demonstrated that marine facies—carbonate rockshave excellent foreground. But reservoir heterogeneity of carbonate reservoir is verystrong, so prediction is hard. The thesis mainly discuss the relationship betweensequence stratigraphy and reservoir of reef and karst, applying Reservoir Geology,well Geology, Seismic strata, Sequence Stratigraphy and other theories to analyze thereef and karst reservoir.Key wells have integrated strata and representative lithology to classify sequencestratigraphic. Then combining seismic data , build isochronous framework to correlatein different orientations. We classify lower-Ordovician three third-order cycles: SSq1,SSq2, SSq3, classify upper-Ordovician four third-order cycles: SSq4, SSq5,SSq6,SSq7.The thesis applies some theories to research reef and karst reservoir inchronostratigraphic framework.Organic reef was affected by many factors : tectonic movement, eustatism, etal.Organic reef developed in tableland border face ,and moved with it . So organic reefdeveloped in two periods . In the first period ,reef distributed along Fault One inTazhong aera;in the second period , it developed in North Slope . Reef mainlydeveloped in upper Ordovician Lianglitage Group . In the chronostrigraphicframework, reef appears in third cycle:Sq11-Sq15.And reef mainly developed aroundsequence boundary in the transgression period, so the development of strata sequencecontrols the reef reservoir .The thesis also analyzes karst reservoir in lower-Ordovician with lithologicalcores and well log data. The strata which Cavernous and fissures developed in welllogs have some characteristics. We use two methods to evaluate excellent karstreservoir : calculate parameters of well logs and make statistics from FMI .Thencombine karst reservoir and sequence strtigraphic framework, we conclude thatsequence boundary has positive controlling effect . The third-order SB causescarbonate rocks exposed seasonally and formed karst in different periods .On the basic of the research ,the thesis predicts two excellent reservoir areas:Fault One in Tazhong area and the Central Fault.