缝洞型碳酸盐岩储层多类多尺度建模方法研究:以塔河油田四区奥陶系油藏为例

Modelling of carbonate fracture-vuggy reservoir:A case study of Ordovician reservoir of 4th block in Tahe Oilfield

碳酸盐岩缝洞型储层历经多期构造运动以及强烈的风化、剥蚀和淋滤作用,储集空间类型多样,形态极不规则且随机分布,导致储层三维空间描述困难,现有的碎屑岩储层建模方法难以直接借鉴。文中提出碳酸盐岩缝洞型储层应该按照大型洞穴、溶蚀孔洞、大尺度裂缝、小尺度裂缝的"多类多尺度建模"的基本思路。以钻井和地震识别成果作为大型洞穴确定性数据,以地震波阻抗的大型洞穴发育概率体作为井间约束数据,在垂向岩溶分带和平面古地貌分区的岩溶相控下,采用具有趋势的序贯指示模拟方法,建立大型洞穴离散分布模型;以大型洞穴分布作为"相控"约束条件,以井孔解释的溶蚀孔洞作为硬数据,采用序贯指示模拟算法,建立溶蚀孔洞随机分布模型;根据蚂蚁体地震属性自动拾取的断裂信息,人机交互补充和修正地震解释断层数据,建立确定性的大尺度裂缝离散分布模型;基于大尺度裂缝离散分布模型建立井间裂缝发育概率体,根据井孔裂缝密度、裂缝产状,结合退火模拟和基于目标的示性点过程模拟方法,建立小尺度裂缝离散分布模型。以塔河油田四区奥陶系缝洞型油藏为例,建立研究区缝洞型储集体空间展布模型,再现缝洞型储层的结构形态。

The carbonate fracture-cavity reservoirs have experienced multiple tectonic movements,strong weathering,denudation and eluviations and the storage space has various types,irregular geometrical shape and stochastic spatial distribution,resulting in the difficulties in 3D description of the reservoirs and direct application of the existing modeling method of clastic rock reservoir.This paper proposed the research idea of classification modeling of large cave,solution pores,large scale fractures and small scale fractures about carbonate fracture-vuggy reservoir.Taking drilling and seismic interpretation as deterministic data of large cave,restrained by large cave development probability cube from seismic wave impedance interwell,under the frame of vertical karst zoning and planar paleogeomorphy division,we use the sequential indicator simulation with a trend to establish the discrete distribution model of large cave;using large cave discrete distribution as the facies controlling condition,taking the solution pores interpretation from borehole as hard data,making use of the sequential indicator simulation algorithm,we establish the stochastic distribution model of solution pores;according to the fault information automatically extracted from seismic ant cube,revising seismic interpretation fault data by man-machine interactive,we build the deterministic discrete distribution model of large scale fractures;obtaining the interwell development probability body of small scale fractures based on discrete distribution model of large scale fractures,integrating the fracture density and attitude of borehole,we set up the discrete distribution model of small scale fractures by combination of the annealing simulation and the object-based marked point processes simulation.Finally we use the above modelling methods,taking the Ordovician carbonate reservoirs in Tahe oilfield 4th block as an example,to set up the geometrical spatial model of fracture-vuggy reservoir.The model can display 3D structure shape of the reservoir.