沾化凹陷长堤地区沙一段生物灰岩发育模式及分布特征

沾化凹陷长堤地区沙一段属于低勘探层段，目前在沙一段下部生物灰岩中钻遇高产油气，沙一段生物灰岩成为勘探热点，而生物灰岩发育模式及分布特征认识不清。以岩芯、录井、测井及三维地震资料为基础，对工区生物灰岩进行系统研究，取得以下几方面认识:1）结合前人层序划分基础，依据地震及井孔资料，将沙一段作为一个三级层序，并利用高频层序划分原理，将沙一段下部细分为三个四级层序，而生物灰岩发育于三个四级层序中；2）生物灰岩分布受古气候、相对古水深和古地貌控制，研究区沙一段时期为亚热带湿润-干旱气候，微咸水湖泊环境，生物灰岩发育在湖平面动荡的湖退体系域中，相对古水深处于稳定的下降过程，录井资料证实生物灰岩多分布于古地貌西南部缓坡及东部洼槽；3）依据主控因素建立生物滩发育模式，划分为缓坡生物滩发育模式和洼槽生物滩发育模式，并确定研究区生物灰岩内幕演化过程，指明研究区发育三期生物灰岩，三期生物灰岩依次向北部长堤潜山呈退积迁移；4）通过对四级层序中生物灰岩垂向发育特征和平面展布特征的分析，并基于敏感地震属性平面分布预测，结合古地貌，确定研究区生物灰岩呈南厚北薄，东部洼槽发育较厚，条带状分布的特征。最后，确定了长堤地区沙一段下部生物灰岩发育模式及分布特征，深化了湖相生物灰发育模式理论研究，为济阳坳陷沙一段特殊岩性油藏勘探和圈闭优选提供指导。

Developing Pattern and Distribution Features of Biological Limestone in First Member of Shahejie Formation in Changdi area,Zhanhua Depression,Bohai Bay Basin,China

High production of oils and gases from the biological limestone at the first member bottom of the Shahejie Formation in Changdi area, Zhanhua sag lead to extremely frequent exploration activities in recent years, which used to be weak in petroleum exploration. Due to a relative low exploration in the whole first member of the Shahejie Formation, the development pattern and distribution features of limestone has not been entirely understood yet. Based on cores, well logs and high-resolution 3-D seismic data, many aspects of the biological limestone have been studied systematically in this paper and several results are summarized as the followings: Firstly, with help of seismic and wellbore data, the first member of the Shahejie Formation is considered as one third-level sequence by the previous method of sequences division, the bottom of which could also be divided into three fourth-level sequences depending on high frequency sequence division theory and the biological limestone developed in this part. Secondly, the distribution of organic bank is controlled by paleoclimate, the relative paleo-water depth and paleogeomorphology, the first member of the Shahejie Formation in the study area existed in subtropical brackish lake environment under a humid-arid climate, and the organic bank was mainly developed in the regressive systems tracting high-energy turbulent lake with a stably declining paleo-water depth. The logging data also confirmed the biological limestone are located in the southwest gentle slope and east depression. Thirdly, the development patterns of the organic bank are established and further divided into gentle-slope and depression patterns. The stratigraphic evolution pattern of the biological limestone is determined for three sets of limestone developed and retrograde to the north. Fourthly, by analyzing vertical and horizontal distribution of biological limestone in each fourth-level sequence, the prediction of horizontal distribution of sensitive seismic attributes and paleogeomorphology, the thickness of the biological limestone is small in north but big in south with a strip-like distribution. Finally, this study determines the distribution and development patterns of the limestone in the lower part of the first member of Shahejie Formation, which deepens the theoretical study on the developing pattern of lake-type biological limestone, and guides the development of lithological reservoir and traps optimization of the first member of Shahejie Formation, Jiyang depression.