高频层序研究在碳酸盐岩储层对比中的应用--以塔河油田TK625井区鹰山组上部储层为例

鹰山组是塔河油田奥陶系油藏主要产层,由于储层非均质性严重,长期以来对其连通性认识不清,严重影响到油田的合理开发.高频层序地层学是研究碳酸盐岩地层形成与分布的有效手段,本文利用高频层序地层学理论和技术方法研究了塔河油田鹰山组上部层序地层特征,将其划分为28个五级层序和4个四级层序,四级层序包括2个退积准层序组和2个进积准层序组.由于四级层序、五级层序是受米兰科维奇天文周期控制的异旋回成因层序,横向变化不大,能够在大范围内追踪对比.因此,根据高频层序划分结果建立高精度的层序地层格架,在此基础上开展储层对比研究.研究表明,塔河油田鹰山组中,孔洞型储层的分布与层序的形成有密切关系,能够在高频层序地层格架内进行对比;裂缝型储层,由于是受后期构造应力作用,横向变化快,相邻井间不具有对比性.

APPLICATION OF HIGH-FREQUENCY SEQUENCE STUDY IN THE CORRELATION OF CARBONATE RESERVOIRS--Illustration in Upper Yingshan Formation around TK625 Well in Tahe Oil Field

Yingshan formation is the major reservoir in Tahe oil field,its connectivity has not been realized clearly because of the severity of heterogeneity,and thus,the development of the oilfield is seriously affected.High-frequency sequence stratigraphy is an available method to study the formation and distribution of carbonate rocks.The upper Yingshan formation in Tahe oil field is analyzed in the light of the theory of high-frequency sequence stratigraphy;it comprise of 4 fourth-order sequences,including two progradation parasequence sets and two retrogradation parasequence sets,and 28 fifth-order sequences.The fifth-order sequences and the fourth-order sequences are controlled by Milankovitch Cycles with minor lateral changes and can be widely correlated.We establish the high-frequency sequences framework with high precision according to the partition of high-frequency sequences and correlate the reservoirs in the oilfield on this basis.Our research shows that the distribution of pore-cave reservoirs in Yingshan formation are tightly related with the formation of the sequences in Tahe oilfield which can be correlated within the framework of the high-frequency sequences.However,fracture reservoirs formed by later structure stresses change quickly between wells and can not be correlated even between adjacent wells.