Abstract

An effective plugging method is proposed for the purpose of solving the problem of steam channeling in the steam stimulation horizontal wells when the steam injection pressure is close to the critical pressure of boiler. The method is successfully applied to several wells in the field. The core of the technology is the original method for calculating the volume of steam channeling, the new plugging agent system and the dam type sealing channeling process. Based on the well logging data, well temperature curve and inters well connectivity, the original method for calculating the volume of steam channeling is determined by theoretical calculation. A new low cost and high temperature resistant agent system has been developed by experiment. The dam type sealing technology is established according to 3D model experiment and numerical simulation.

The results show that the probability of occurrence of steam channeling is significantly increased when the permeability difference is greater than 4. The location of steam channeling is high permeability layer and small well spacing. The original calculation method of steam channeling volume can accurately predict the dosage of the plugging agent.

The new low cost and high temperature resistant agent system is a solution system without solid particles, which is based on inorganic materials, organic materials as the inducing agent and surfactant as the stabilizer. The viscosity is about 3mPa.s at room temperature. The system begins to solidify at 80°C and forms the bulk solid state finally. The system can be able to bear 350°C, and the residual resistance coefficient is as high as 30.

The technical core of the dam type sealing technology is the alternate combination of high strength slug and weak strength slug. The role of the high strength slug is sealing of the steam channeling while the role of the weak strength slug is adjusting the subsequent injection pressure. The total dosage of plugging agent is 0.4 times of the volume of steam channeling. According to the intensity of steam channeling and the size of steam injection pressure, the high strength slug is 1/3~1/2 times of the dosage of the total blocking agent. The high permeability layer is not only the steam channeling, but also the flow passage of crude oil. The high permeability layer is not completely blocked, so the yield of the subsequent crude oil is not affected. The dam type sealing technology can effectively control the subsequent injection pressure, and does not affect the crude oil production.

The advantage of this technology is effective steam channeling plugging, suitable injection pressure and high yield of crude oil, and this technology has very important significance for the exploitation of heavy oil steam stimulation.

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