鄂尔多斯盆地合水地区长6储层成岩作用与有利成岩相带

Diagenesis and Favorable Diagenetic Facies of the Chang 6 Reservoir in Heshui Area,Ordos Basin

鄂尔多斯盆地合水地区长6储层主要为长石岩屑砂岩,平均孔隙度8.68%,平均渗透率0.15×10-3μm2,属于典型的低孔特低渗透储层。储层经历了压实作用、胶结作用、交代作用、溶蚀作用的改造,目前处于晚成岩阶段A期。在成岩作用研究的基础上,通过大量的岩心观察、薄片鉴定、扫描电镜等方法及测井曲线特征研究,进行了单井成岩相分析,进而编制成岩相平面分布图。将研究区辫状河三角洲前缘砂体划分出4个成岩相带:压实相、碳酸盐胶结相、绿泥石膜剩余孔相和绿泥石膜剩余孔—长石溶蚀相。其中,有利储层主要分布在主砂体的绿泥石膜剩余孔相和绿泥石膜剩余孔—长石溶蚀成岩相带上。根据试油资料,处于该有利相带的井一般日产油大于10t/d。

The Chang 6 sandstone reservoir in Heshui area, Ordos Basin, is manily composed of feldspathic litharenite sandstone and litharenite. It is of typical low porosity and low permeability reservoir with average porosity of 8.68% and average permeability of 0.15 × 10-3 μm2. The reservoir has experienced compaction, cementation, metasomasis and dissolution, and is now in the late diagenetic phase A. On the base of diagenesis research, it sets up the single well diagenetic facies by many ways of core observation, cast section, SEM and the logging analysis. Then the paper analyses areal distribution graph of diagenetic facies. The braided river delta front sandbody in the study area can be divided into 4 diagenetic facies belts, including compaction, carbonate cementation, chlorite film residual pore and chlorite film residual pore- feldspar corrosion. The advantaged reservoir is distributed at the latter two facies belts. The oil production of well in the adwantage belt is more than 10 t/d according to the test oil data.