Oil-based ultrafine cement paste and production method thereof

Abstract

An oil-based ultrafine cement paste consists of ultrafine cement, diesel oil and oil-soluble surfactant which are calculated according to per cubic meter of diesel oil, and the oil-based ultrafine cement paste contains 1.5 to 3.0 tons of ultrafine cement and 3 to 10 kilograms of oil-soluble surfactant; and the ultrafine cement consists of 50 to 70 percent of cement with the grain size distribution of 10Mu m to 15Mu m and 30 to 50 percent of cement with the grain size distribution of 30Mu m to 35Mu m. Since the grain size distributions of the ultrafine cement in the oil-based ultrafine cement paste disclosed by the invention are in two intervals, the oil-based ultrafine cement paste not only can enter deep formation pores to selectively block water, but also can be applied in formations with complex pore size distribution. Ultrafine gypsum powder can be added in the oil-based ultrafine cement paste disclosed by the invention as well, so that the volume of a solidified cement block can be kept unshrunk under the circumstance that the strength of the ultrafine cements is kept, moreover, by controlling the sequence of adding the oil-soluble surfactant and water-soluble surfactant, the ultrafine cements can be uniformly distributed, and the dewatering effect is remarkable.

Description

technical field [0001] The invention relates to a water shutoff agent in oil exploitation, in particular to an oil-based superfine cement slurry for selective water shutoff and a preparation method thereof, belonging to the technical field of oil exploitation. Background technique [0002] In the process of water flooding in oilfields, due to the extreme incompatibility between the water phase and the oil phase, it is easy to form a state where water flows in front of the oil phase during water breakthrough or formation water migration, causing water to block the oil phase, resulting in oilfield failure. Mining produces water but not oil. In order to solve this problem and improve the efficiency of oilfield water injection production, in the prior art, the commonly used technical means is water plugging, that is, blocking the water flow channel to form a new oil flow channel, so as to ensure that the oil phase can flow out of the non-water flow channel . [0003] In practi...

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Problems solved by technology

[0006] The technical problem to be solved by the present invention is that in the prior art, when cement slurry is used for selective water plugging, since the deep pores of the formation are often large and small, the conventional cement particles are large and cannot enter the depth of the formation pores; Cement is often not suitable for complex formations with wide pore size distribution, thus providing an oil-based ultra-fine cement slurry with good selective water shutoff performance that can be achieved through particle size coupling compounding

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