蒙古国东方省海塔盆地塔南凹陷断裂特征及其油气意义

Characteristics of fault structure in Tanan Sag, Haita Basin in Dornod Aymag, Mongolia and its hydrocarbon significance

以三维地震资料解释为基础,通过编制相关构造图件揭示了海塔盆地塔南凹陷的断裂构造特征和构造演化过程,分析了构造活动对沉积作用的控制以及对烃源岩发育、圈闭形成和油气运移聚集条件的影响。塔南凹陷白垩纪经历了叠合断陷期(铜钵庙组—南屯组沉积时期)、叠合断拗期(大磨拐河组沉积时期)和反转拗陷期(伊敏组—青元岗组沉积时期)共3期演化,发育伸展和走滑—伸展两套断裂系统。受断裂活动影响,不同时期各次凹的沉降中心发生了明显的分异与迁移。断陷期沉降中心沿断陷边界断层上盘分布,断拗期沉降中心向凹陷中心迁移。断陷期结构样式及主干断裂活动强度控制着沉积相的分布,也影响油气成藏。

Based on structural geometry data compiled by interpretation of 3D seismic data in Tanan Sag of Haita Basin, the faults characteristics and evolution, and their controls on sedimentation and hydrocarbon source rocks, trap, and accumulation were analyzed in this paper. It is found that the Tanan Sag had gone through three big basin historical periods, that is, composite faulted stage （Kit-Kin） , the composite fault-depression transition stage （Kid） and reverse depression stage （Kly-K2q） , and normal fault system and strike-slip normal fault system formed during the Cretaceous. Affected by faults move-merit, the subsidence centers in sub-sag were differentiated and migrated distinctly in different stages. The subsidence center distributed along the hanging wall of the boundary faults during the composite faulted stage, and moved to the center of the sag during the composite fault-depression transition stage. The strength and style of the faults controlled the distribution of sedimentary facies and hydrocarbon accumula- tion conditions.