含水油藏的形成、评价和勘探——关于一种可能的新油藏类型的探索

Formation, evaluation and exploration of water-bearing oil reservoirs: search after a possible new reservoir type

含水油藏一般见于中 -低孔、低 -特低渗透率碎屑岩储层中。严重的非均质性是其突出特点。微观上 ,碎屑岩内部具有赋存液态石油的自流孔喉系统和饱和着原生地层水的滞流孔喉系统双重孔隙结构。其中 ,自流孔喉系统中含有自由水 ;滞流孔喉系统中主要赋存有微细孔隙水、微孔隙水、死孔隙水、和分子结合水。滞流孔喉系统在岩石孔隙体积中占有相当大的比例 ,制约着油水的产出情况 ,并导致了多数含水油藏的含油饱和度不足 5 0 %。含水油藏 (层 )形成的地质条件主要与二连中生界裂谷盆地群碎屑岩结构、组分成熟度过低及因成岩作用而物性急剧变差有关。在当前经济和技术条件下 ,含水油藏尚处于商业开采边沿 ,因此 ,应依据岩心含油、岩心滴水试验、气测录井、薄片鉴定、物性分析、压汞试验、核磁共振测量、油层测试等方面的特征 ,尽早对含水油藏 (层 )进行动态识别与评价 ,以避免实物工作量的无效投入。

Water-bearing oil reservoirs generally occur in medium-low porosity and low-ultra low permeability clastic rocks and have the prominent characteristics of strong heterogeneity. Microscopically, clastic rocks have dual-pore structures, i.e. artesian pore throat system with the occurrence of liquid hydrocarbons and stagnant pore throat system saturated with original formation water. The artesian pore throat system contains artesian water, while the stagnant pore throat system mainly contains fine pore water, micropore water, stagnant pore water and molecular bound water. Stagnant pore throat system, accounting for a large proportion of pore volumes, would not only constrain production of oil and water, but also lead to the oil saturation of most water-bearing reservoirs to be below 50%. The geological conditions of formation of water-bearing reservoirs are related mainly to the structure of clastic rocks, extremely low compositional maturity and the poroperm characteristics drastically become poor due to compaction in the Mesozoic rift basin groups in Erlian. In the present economic and technical conditions, water-bearing oil reservoirs are still on the margin of commercial recovery, thus dynamic identification and evaluation of water-bearing oil reservoirs should be performed as early as possible according to oil-bearing condition of cores, water dropping test of cores, mud logging, thin-section analysis, poroperm analysis, mercury injection test, NMR and reservoir testing, so as to avoid ineffective investment.