塔河油田奥陶系碳酸盐岩储层的测井解释

LOG INTERPRETATION OF ORDOVICIAN CARBONATE RESERVOIRS IN TAHE OILFIELD

根据测井响应的不同 ,可将塔河油田奥陶系碳酸盐岩储层划分为 3类 ,Ⅰ类为裂缝 -孔洞和裂缝 -溶洞型 ,深浅侧向电阻率低 ,为正幅度差 ,自然伽马值略高 ,声波时差和中子测井值增大、密度降低 ;Ⅱ类储层为裂缝型 ,深浅侧向电阻率呈中 -较高值 ,大部分为正幅度差 ,自然伽马特征与灰岩相近 ;Ⅲ类为孔洞缝均不发育的储层 ,电阻率为高值 ,深浅侧向电阻率基本重叠 ,自然伽马为低值。在测井曲线标准化和岩芯归位基础上即可进行储层参数的求取。参数主要包括泥质含量、基质孔隙度、裂缝孔隙度、总孔隙度、洞穴孔隙度、原始含油饱和度与基块、裂缝含油饱和度。依据参数与测井资料确定的基块孔隙度和裂缝孔隙度下限值分别为 2 和 0 0 5 。经验证 ,测井解释的孔隙度与实际总体相符 。

Ordovician carbonate reservoirs in Tahe Oilfield could be divided into three types.Type I is fracture pore and fracture solution cavity resavoirs with low laterolog resistivity of both shallow and deep formations,high gamm ray value,increased acoustic time and neutron log valuse;type Ⅱ is fracture reservoirs with mid higher laterolog resistivity of both shallow and deep formations,gamma ray value similar to that of limestone;type Ⅲ is poor in fractures and pores, but the highest resistivity,low gamma ray value,and overlapped shallow and deep laterolog resistivities.Then reservoir parameters could be calculated through well log normalixation and core reposition.Accordineg to the calculated parametres and log data,the lower limits of rock mass porosity and fracture porosity are 20/0 and 0 050/0 respectively.The fracture porosity of the reservoirs are determined to be≥0 050/0,≥0 050/0and <0 050/0,and their pore porosity≥20/0,<20/0 and <20/0 respectively.It has been proved that well log interpreltation results fit in with the actural porosity and fractural distribution of the reservoirs studied.