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奥里诺科油田发育重质油藏,测井和岩心研究结果表明,随着钻井位置逐渐远离现有的生产井,储层性质也变得愈发复杂,出现了一些薄层、淡水层、生物分解油或沥青、低阻油层以及气层等。在原油粘度达到纯水粘度一万倍的情况下,预测产水层就成了必须做的工作。之前的奥里诺科带生产开发经验表明,地层电阻率和持水率并没有直接的联系,具有相似电阻率的储层有时候产油,也有时候会产水。在以前开发奥里诺科带时,NMR主要是用来连续的计算粘度来识别水层,避免在设计水平注水的时候穿过水层。具有浅探测深度的早期NMR工具很适合这项工作,除了不规则井眼(这在一些未固结的奥里诺科储层来说很常见)。最近,通过系统的采集4寸探测深度上的核磁资料,然后用四维(4D)NMR反演技术处理所测资料的新型多切片测量方式已经从根本上解决了冲洗带和井眼不规则问题。实践表明,4寸的探深已经到达了不受泥浆滤液影响的原状地层。这样,探测更深地层的NMR就能告诉我们储层的水是可动水还是不可动水。
The Orinoco field has developed heavy oil reservoirs. Well logging and core studies have shown that the nature of reservoirs has become more and more complex as drilling locations gradually get farther away from existing production wells, with some thin layers, Biodegradable oil or bitumen, low resistivity oil and gas layers. Predicting the aquifer is a must-do when crude oil viscosity reaches 10,000 times the viscosity of pure water. Previous Orinoco production experience shows that there is no direct correlation between formation resistivity and water holding capacity, reservoirs with similar resistivities sometimes produce oil and sometimes produce water. In the previous development of Orinoco bands, NMR was mainly used to continuously calculate the viscosity to identify the water layer and avoid passing through the water layer at design level. Early NMR tools with shallow depths of exploration were well suited for this work, except for irregular boreholes (as is common in some unconsolidated Orinoco reservoirs). Recently, the problem of flushing zone and wellbore irregularities has been fundamentally solved by the systematic acquisition of NMR data at a depth of 4 inches and then the processing of the measured data using four-dimensional (4D) NMR inversion techniques. Practice shows that the 4-inch exploration depth has reached the undisturbed formation affected by mud filtrate. In this way, the NMR of the deeper layers can tell us whether the reservoir water is moveable or not.