Experimental study of water-rock reaction during thermal production

The speed and degree of water-rock reaction will increase with temperature, and mineral fines produced by chemical reaction contribute mainly to pore block when temperatures reach 200-300°C. Take petroliferous fine siltite (S1) and oil-rich siltite (S2) of Gudao field as experimental samples, this paper has studied the water-rock reaction mechanism at different temperatures and initial pH values of injected fluid. The experiment indicates that the dissolution and precipitation of minerals is the main factor to cause reservoir damage. At high temperatures, the primary minerals in sand reservoir, such as quartz, potassic feldspar, sodium-calcium feldspar, dissolve and new minerals produce. The precipitated minerals become the main source to pore block. The experiments of different initial pH values show that when pH value is 9, the solution of minerals is most for clay-rich rock, and the solution of minerals is least for clay-poor rock.