塔中地区奥陶系碳酸盐岩储层测井评价研究

Well logging evaluation of Ordovicinn carbonate reservoir in central Tarim basin.

缝洞型碳酸盐岩储层评价是西部新区油气勘探需要解决的难题。针对塔中地区K1区块碳酸盐岩储层特点,探讨利用能谱测井和常规测井资料的综合信息对地层进行划分和储层对比,提出了以能谱测量比值的组合交会为基础的测井特征比值参数法来研究碳酸盐岩地层的沉积特性,确定了油区奥陶系碳酸盐岩风化面及其风化壳的深度和厚度,指出能谱铀相对含量远大于钍/铀比的地方为岩溶、裂缝发育的淋滤相带(岩溶淋滤带),应在此带内寻找岩溶储层；建立了奥陶系测井地层划分模式,认为上奥陶统良里塔格组泥灰地层沉积稳定,为区域标志层,风化壳岩溶作用导致鹰山组广泛发育岩溶,是塔中的主要油气聚集层位。利用试油资料,进行交会图分析,开展储层标准研究,建立了常规测井资料的3级分类标准。在缝洞型储层处理的基础上,结合成像测井进行储层重新评价,经过K1区块5口井的实测验证,认为采用上述多参数综合解释方法来划分地层和评价储层是可行的。

The evaluation of fracture-cavern carbonate reservoir is diffi- cult in the new development area of western China.Aimed at the K1 block in Tazhong area,the synthetic information of in-hole spectrometry data as well as conventional logging data is used to delineate stratua and correlate reservoirs,a logging characteristic parameter method based on the composition and intersection of in- hole spectrometry is proposed to study the sedimentary features of carbonate formation,and the exposed surface of the Ordovician carbonate is verified.The depth and thickness of the weathering crust is determined.The authors point out that the leached zone with karst-fraeture developed exists in those places where the rela- tive content of energy U is much greater than the TH/U ratio and the karst reservoirs should be found in this belt.The logging strata division mode of Ordovician is established.Because the muddy limestone strata of Lianglitag formation of Upper Ordovician has a steady deposition,it can be used as a regional marker bed;the karstification of weathering curst causes the Yingshan formation to be widely developed and become the main hydrocarbon accumula- ting layer.By using test data,cross plot is analyzed,reservoir cri- teria studied.On the basis of this,a three-level classification crite- rion for conventional logging data is established.Based on the karst-fracture reservoir theory and imaging logging,the reservoirs are re-evaluated.The application of the above mentioned methods in dividing the strata and reservoir of five wells in K1 block is proved to be feasible.