Abstract

The study of the change in the composition of the seawater injected for reservoir pressure maintenance (RPM) to the anhydrous granitoid reservoir of the White Tiger oil field, in which the cracks are partially filled with calcium minerals (calcite and laumontite), has shown that these minerals interact with injected seawater. Hydrogeochemical modeling of this process has revealed that the seawater cations (first sodium and then magnesium) displace calcium from the laumontite exchange complex, which leads to precipitation of anhydrite and a small amount of calcite. The incoming water dissolves the anhydrite and precipitates it downstream, forming a gradually expanding annular region with a constant increase in the amount of precipitated anhydrite. As a result, there is a decrease in the permeability of the fractured medium due to the anhydrite filling of the cracks. A large amount of calcium in the produced waters upon their rise to the surface causes the calcite precipitation in the production wells and the surface equipment. The transition of drilling to greater depth, where the rocks contain laumontite almost everywhere, requires considering the phenomena of cation exchange between the injected water and the rock in the predictions of scaling.

中文翻译：

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阳离子交换作用在油田开发中的储集岩准集作用

摘要

对白虎油田无水花岗岩储层维持储层压力维持（RPM）注入的海水成分变化进行的研究表明，裂缝中部分充满了钙矿物质（方解石和月桂石）。这些矿物质与注入的海水相互作用。此过程的水文地球化学模拟表明，海水阳离子（先是钠，然后是镁）取代了月桂石交换复合物中的钙，这导致硬石膏和少量方解石沉淀。进入的水溶解硬石膏，并使其沉淀到下游，形成逐渐膨胀的环形区域，其中硬石膏的沉淀量不断增加。结果是，由于裂缝的硬石膏填充，导致裂缝介质的渗透率降低。采出水中的大量钙上升到地表时，会在生产井和地面设备中引起方解石沉淀。钻探过渡到更大的深度时，在岩石中几乎到处都含有月桂石，这需要在水垢预测中考虑注入的水和岩石之间的阳离子交换现象。