东濮凹陷文东地区沙三段层序地层学特征

Sequence Stratigraphy of Es_3 Member in Wendong District, Dongpu Depression

运用层序地层学理论,通过钻井高精度层序地层分析(包括单井岩心沉积相分析、单井高精度层序地层分析、联井高 精度层序划分对比),结合地震层序分析,东濮凹陷文东地区沙三段(Es3)可划分为4个三级层序:SQ1、SQ2、SQ3、SQ4,可识 别出4种主要沉积体系:湖泊三角洲体系、湖泊体系、重力流体系、扇三角洲体系.综合前述特征,文东地区沙三段层序地层 学特征表现为:SQ1在文东斜坡带上发育浅湖相,局部地区发育重力流沉积;东侧发育扇三角洲体系,并逐渐退积.SQ2— SQ4文东斜坡带上主要发育湖泊体系(滨湖、浅湖、半深湖和盐湖)与湖泊三角洲前缘亚相;东侧主要为扇三角洲体系,规模 较小.结合层序地层与沉积学特征分析,湖泊三角洲前缘砂体、扇三角洲砂体、重力流砂体是文东地区有利的储集体.

Wendong district is a very important exploration area in Dongpu depression, and the sequence stratigraphy study is critical to find subtle trap and increase reserve and production in this district. Based on the analysis of high-resolution sequence stratigraphy in well logs (including core facies analysis, single well sequence analysis and cross wells sequence division), and interpretation of sequence stratigraphy in seismic sections, the Es3 member in Wendong district, Dongpu depression is divided into four third-order sequences: SQ1, SQ2, SQ3 and SQ4. Four main sedimentary systems can be identified in Es3. They are lacustrine-delta system, lacustrine system, gravity flow system and fan delta system. The former opinions show that shallow lake developed on the Wendong slope, gravity flow system developed in topical place and fan delta system developed in the east reigion and regressed gradually in SQ2. From SQ2 to SQ4, lacustrine system (including lacustrine beach, semideep lake, deep lake and saline lake) and the front of lacustrine delta developed on the Wendong slope; at the same time, fan-delta system developed in the east region and the scope became small. On the basis of the analysis of sequence stratigraphy and the depositional system, the front sand body of the lacustrine delta, and the sand bodies of the fan-delta system and gravity flow are favorable targets to explore lithologic reservoir and lith-structural reservoir in Wendong district.