Adsorption inhibitor applying to low permeable oilfield

Abstract

The invention relates to an adsorption inhibitor which is applied to low permeability oilfield. According to the mass percentage, the inhibitor comprises 0.5-2% of bis-quaternary ammonium salt, 0.2-1% of single-chain small cation organic polymer, 2-5% of inorganic salt, 0.1-0.3% of chelating agent and residual quantity of water; the adsorption inhibitor restrains the expansion displacement of clay and leads the crystal lattice of expanded clay to release contracted water molecular crystal lattice by the modification through the chemical reaction; the inhibitor has strong adsorption performance, can resist washing, has a certain activity, rapidly reduces the surface tensile force, changes the surface wettability of the rock and clay minerals, and can restrain the adsorption of other matters on the surface of rock minerals, thus improving the stratum seepage capability and achieving the object of pressure reducing and injection increasing.

Description

Technical field: [0001] The invention relates to a chemical preparation injected downhole in the field of oil production in oil fields, in particular to an adsorption inhibitor applied to low-permeability oil fields. Background technique: [0002] Low-permeability sandstone oilfields are mostly siltstone and fine sandstone minerals. The reservoir has small pore radius, poor development, high clay and shale content, severe sensitivity and high seepage resistance. During the waterflooding development process of this type of oil layer, there are two important reasons for the rapid decline of formation permeability: the reduction of pore space due to clay expansion; and the bridging of throat holes due to clay dispersion and migration with fluid. The swelling and dispersion of clay particles is not an independent process, but is essentially caused by the adsorption of water molecules on the mineral surface through hydrogen bonds to form a hydration layer. Water lock, water sens...

AI Technical Summary

Problems solved by technology

Water lock, water sensitivity, water incompatibility pollution and other formation damage are serious, causing injection pressure to rise, water cannot be injected, and injection cannot be completed, resulting in low production of oil wells

What's more serious is that the expansion of the formation with high clay content will cause the casing to be deformed or broken, resulting in failure to produce

The types of clay stabilizers currently used are basically high-salinity inorganic brines (such as KCL, NaCL, NH 4 CL, etc.) and organic polyquaternary ammonium salts, which are not resistant to fluid erosion when applied to low-permeability and high-clay muddy reservoirs. Short and so on

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