Abstract
Water block damage is the core problem in damage to tight gas reservoirs, and the main obstacle to developing these reservoirs. When an ionic carbide (aluminum carbide: Al4C3) drying agent is injected into the reservoir, the water is quickly gasified through a drying treatment to improve the seepage capacity of the gas and the recovery rate of the reservoir. However, under high temperatures and high pressure (HTHP) conditions, it is easy to lose the reactivity due to the high activity of the drying agent, thus preventing the drying effect. In this paper, in order to delay the reaction starting time of the Al4C3 in HTHP conditions with water-cut, a surface modification of aluminum carbide was carried out by using absolute ethyl as the reaction media and polyvinylpyrrolidone (PVP) as a modifier under the reaction of an initiator AIBN. The modified Al4C3 was characterized by SEM, TEM, FTIR, and other detection methods. In addition, a gas evolution experiment compared the starting time of the reaction between unmodified aluminum carbide and formation water to the starting time of the reaction between modified aluminum carbide and formation water. Results show that this method can successfully modify the drying agent and effectively block the reaction activity of the drying agent. Meanwhile, gas production in the process of drying and the consumption of formation water are obviously reduced, which can effectively delay the reaction starting time by 6-8 minutes.
Highlights
Tight sandstone gas reservoirs have a wide exploration field in China: it is predicted that the tight gas prospect resources there range from 12×1012 to 100×1012 m3.1,2 Tight gas is playing an increasingly important role in reserve growth and energy supply, and will eventually succeed conventional oil and gas resources in China
Because of the constant temperature magnetic stirring is used in the reaction kettle, so the aluminum carbide can be fully dispersed
IT can be concluded that the modification of aluminum carbide has been successfully performed by solution polymerization with the action of the initiator AIBN
Summary
Tight sandstone gas reservoirs have a wide exploration field in China: it is predicted that the tight gas prospect resources there range from 12×1012 to 100×1012 m3.1,2 Tight gas is playing an increasingly important role in reserve growth and energy supply, and will eventually succeed conventional oil and gas resources in China. During the development of tight sandstone gas reservoirs, the gas flow in the reservoir is narrow, the seepage resistance is large, the interaction between the liquid-solid interface and the gas-liquid interface is large, and the water blockage effect is prominent. This is because of the reservoir’s unique engineering and geological characteristics of low porosity and low permeability. This study’s primary task is to develop a scientific and reasonable method to modify the main drying agent, I order to delay the start-up time of the drying reaction and satisfy the drying requirements for tight gas reservoirs. This paper presents a solution polymerization method, through the action of the initiator (AIBN), for successfully modifying the carbide by polyvinylpyrrolidone (PVP)
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