Watercut Difference Study In Initial Production Stage Of Low-permeable Oil Reservoirs

Development of low-permeable reservoirs is critical to mature oilfield such as Shengli due to much OOIP in them. But the reservoir characteristics and water saturation distribution is severe heterogeneous, which restraints development of such kind of reservoirs with high efficiency. So the research of the factors which controlling initial water saturation distribution is important.Block Fan31 and Zhuang74 are such low-permeable oil reservoirs with heterogeneous water saturation distribution and poor reservoir characteristics. And production performance is complex with no obvious regular pattern. At first by multiple advanced experiment and assay techniques, rock type, authigenic mineral properties, clay type/occurrence-mode, pore type and pore-throat configuration are determined. Then based on detailed strata correlation/zonation, detailed sedimentary microfacies analyses and study of relationship between reservoir petrophysical characteristics and sedimentary microfacies, reservoir heterogeneity and its influential factors are probed.According to log-interpreted water saturation distribution, dynamic-analyzed water saturation distribution in initial development stage, core-analyzed water saturation, NMR-interpreted water saturation and pore-throat calculated water saturation, initial water saturation distribution of actual low-permeable reservoirs in work area are studied laterally and vertically. Then based on well log, formation testing, dynamic data in initial development stage, difference of initial water saturation distribution of Block Fan31 and Zhuang74 and its influential factors are analyzed.