SWD地区隐蔽圈闭的识别

SWD地区主要勘探目的层侏罗系三工河组二段（J1s2）呈南倾单斜形态，构造简单，断层不发育，勘探对象为地层隐蔽圈闭。主要勘探目的层砂体为曲流河三角洲前缘分支河道砂体，具有河道顶部细粒成分保存好、粒度小、砂（砾）岩相对不发育、平面上岩性变化快的特点，容易形成“典型”的砂岩尖灭油气藏，识别和描述该类圈闭的难度较大。该区地震资料优势频率达45～55Hz，能分辨的地层最小厚度约为25m，可为该区隐蔽油气藏勘探提供较为可靠的资料依据。本文从该区的地震地质特征出发，通过主要目的层层序地层划分、精细层位标定、地震正反演研究，建立了地震地质解释模式；应用地震属性分析技术研究沉积相和砂体展布规律，结合测井约束反演技术，有效地识别和描述了隐蔽圈闭。其中S4块J1s2岩性圈闭已为后期的钻探证实。

Recognition of subtle traps in SWD area.

The major prospecting target in SWD area is Jurassic Sangonghe Group Second Segment (J1S2) that is characteristics of south-inclined single-slope configuration, simple structure and undeveloped faults,and the exploration objects are subtle strata traps. The major prospecting objective sand body is meandering river delta front branching channel sand body that is characteristics of good reservation of fine-grained contents on the top part of channels, smaller grain grade, relatively undeveloped sand (gravel) stones and rapid variation of lithology on plane,which easily forms typical sandstone pinch-out reservoir that is difficult to identify and describe this kind of traps. The dominant frequencies of seismic data in the area are 45-55Hz and identified minimum thickness of strata is about 25m,which can provide more reliable data foundation for subtle reservoir exploration in the area. Coming from seismic and geologic feature in the area, the paper created seismic and geologic interpretation mode through stratigraphic-sequence division of major targets, fine horizons labeling and seismic forward and inversion studies;effectively i-dentified and described subtle traps by using seis- mic attributes analysis techniques to study sedimentary facies and distribution regularity of sand bodies and combining with logging-constrained inversion technique, among which J1S21 lithologic traps in S4 block has been proved by latter drilling results.