摘要：
The Lixian slope of Raoyang sag in Jizhong depression has received numerous attentions because of its richness in oil and gas production.With the improvement of petroleum exploration and exploitation, the lithologic-stratigraphic reservoirs are becoming an important target for petroleum promotion, and identifying the genetic types and distribution and evolution of sand bodies is the key of efficient petroleum exploration and exploitation.The seismic sedimentology of the lower part of the first member of Shahejie Formation in Lixian slope was studied based on core, well logging and three-dimensional seismic data.The study interval corresponds to a set of a fourth-order sequence, which is bounded by T4and T42seismic markers, respectively, and the seismic marker of T43is also identified internally;thus, the lower part of the first member of Shahejie Formation can be subdivided into the bottom sandstone section and the special lithologic section.The bottom sandstone section related to the shallow-water deltaic origin can be subdivided into three sub-facies types, including shallow-water delta plain, shallow-water delta front (inner front and outer front) and pro-shallow-water delta;the special lithologic section is characterized by lacustrine beach-bar deposits, and the types of the associated sand bodies are predominantly constituted by sandy clastic beach-bar, followed by carbonate beach-bar.During the sedimentary period of bottom sandstone section, the shallow-water delta system shows obvious zonation in plane, and the underwater distributary channel sandstones in the inner front of the shallow-water delta has a wide distribution range with a maximum transport distance of 15km, which are proven good reservoirs in the study area;from early to late, with the lake level rising gradually, the sediments provided by the southwestern provenance gradually become predominant, while the supply from the northern provenance system shrinks.During the sedimentary period of special lithologic section, the lake level rises abruptly.Consequently, the shallow-water delta system almost withdraws from the study area, and the shallow lake to deep lake together with beach-bar deposits become dominated, and the main type of the associated sand bodies is sandy clastic beach-bar, which is located in the eastern part of the study area (the area is about 12km2) with paralleling to the lake shoreline in a strip geometry.Based on sedimentology and seismic sedimentology, the depositional models of the bottom sandstone section and the special lithologic section are established, which can provide potential references for reservoirs prediction and petroleum exploration and exploitation in the future.%冀中坳陷饶阳凹陷蠡县斜坡因富含油气而备受关注,随着勘探程度的不断提高,岩性-地层油气藏成为蠡县斜坡增储上产的主要目标,明确砂体成因类型及其分布演化规律是油气高效勘探开发的关键.综合利用岩芯、测井和三维地震资料,开展了蠡县斜坡北段沙一下亚段地震沉积学研究.依据沙一下亚段顶、底界面T4和T42地震反射标志层以及内部T43地震反射标志层,将沙一下亚段划分为尾砂岩段和特殊岩性段.浅水三角洲成因的尾砂岩段可细分为浅水三角洲平原、浅水三角洲前缘(内前缘和外前缘)及前浅水三角洲等3种亚相类型;特殊岩性段以滩坝-湖泊沉积为特征,砂体类型主要为砂质碎屑岩滩坝,碳酸盐岩滩坝次之.尾砂岩段沉积时期,浅水三角洲体系在平面上表现出明显的分带性,浅水三角洲内前缘水下分流河道砂体分布范围广,最大推进距离达15km,是研究区的主力储层;从早到晚,伴随着湖平面逐步上升,西南部物源逐步占据主导地位,而北部物源影响范围减小.特殊岩性段沉积时期,湖平面迅速上升,浅水三角洲体系完全退出蠡县斜坡北段,沉积体系以滨浅湖—半深湖和滩坝沉积为特征,砂体类型主要为砂质碎屑岩滩坝,分布在研究区东部(面积约12km2),大多平行于湖岸线呈条带状展布.根据沉积学和地震沉积学研究,分别建立了研究区尾砂岩段和特殊岩性段时期的沉积模式,为下一步储层预测和油气勘探开发提供参考.
