沉积盆地断裂趋势带形成演化及其控藏作用

断裂趋势带是指盆地沉积盖层内的弱变形构造带，属于断裂带形成演化早期或中期阶段的产物.沉积盆地断裂趋势带隐蔽性较强，识别标志不明显，往往被忽视，因而在断裂趋势带上未发现油气藏的区域应该是未来油气勘探值得重视的领域.根据断裂趋势带的规模可将其划分为:(1) 圈闭级断裂趋势带，特征是多个雁列式断块、弧形断块或者复合型断块圈闭呈线状排列组成；(2) 洼陷级断裂趋势带，表现为雁列式展布的多条断裂或褶皱，其间由小断层断续相连；(3) 凹陷级断裂趋势带，表现为洼陷、凸起、沉积相带或圈闭等构造单元呈线状断续相间排列；(4) 坳陷级断裂趋势带，属于区域性隐性断裂，一般表现为沿固定方向基底埋深突变、沉积盖层厚度突变、沉积相带突变等特征；(5) 盆地级断裂趋势带，表现为成排成带的低幅度构造定向延伸组合成的大规模鼻状褶皱带或大型低幅度隆起.另外，结合构造物理模拟实验建立了基底断裂走滑型断裂趋势带的5阶段演化模式分析认为，断裂趋势带油气聚集模式可以概括为6种:雁列状断块聚集模式、带状断块聚集模式、雁列状褶皱聚集模式、平行状复合圈闭聚集模式、网格状复合圈闭聚集模式、环状复合圈闭聚集模式. 

Formation and Evolution of Concealed Fault Zone in Sedimentary Basins and Its Significance in Hydrocarbon Accumulation

Concealed fault zones are a type of weak deformation fault zones that form in sedimentary covers and have expressive forms of faults that show in the early-middle stage of their formation and evolution processes. It can be found by reservoirs, sedimentary facies, sags (depressions) and ridges ranged regularly. Concealed fault zones are supposed to be potential direction for future exploration since reservoirs are usually distributed in concealed fault zones, displaying en-echelon, string or belt patterns. On the vacant area of concealed fault zones should be worthy of oil and gas exploration area in the future According to the scale, concealed fault zones are classified into 5 types in this paper: (1) the trap scale concealed fault zone consists of a series of en echelon fault blocks, curved blocks or compound blocks in line; (2) the sub-sag scale concealed fault zone composed of a lot of faults and folds, with the distribution of echelons and string of many small faults; (3) the sag scale concealed fault zone showing that there is an intermittent string of sub-sags, ridges, sedimentary facies or traps; (4) the depression scale concealed fault zone identified by the mutation of basement depth, the thickness of the sedimentary cover and sedimentary facies, belonging to regional-concealed fault; (5) the basin scale concealed fault zone characterized by large-scale nosing folds or low-amplitude ridges ranged in defined rows. In addition, the evolution model of concealed fault is established under the evolution of transtensional regional stress field and basement fault activities combined with the structural analogue experiments. It is found that concealed fault zones have controlled the accumulation of the oil and gas in the following six patterns: en echelon fault block accumulation pattern, banded fault block accumulation pattern, en echelon fold accumulation pattern, an accumulation pattern of parallel combination traps, an accumulationpattern of grid combination traps, an accumulation pattern of circularity combination traps.