Blockage formation in water-flooding heavy oil reservoirs: The distribution rule and the scaling mechanism

Abstract

Blockage is a common problem in the development of water-flooding reservoirs. The key to solve this problem is to determine the composition and distribution rules of the blockage. In this work, the location distribution and components of blockage were analyzed by one-dimensional (1D) and two-dimensional (2D) cores, and x-ray diffraction and differential weight methods. The blockage formation mechanism was also studied. The 1D experimental results show that the blocking locations of the inlet and outlet ends are 3/10 and 8/10, respectively (1D core is divided into 10 equidistant sections; “3/10” refers to the three sections from the inlet end and “8/10” refers to the two sections from the outlet end). The blockage near the inlet is mainly composed of inorganic scale, which is formed by a combination of the carbonate and coarse sand particles. However, the blockage near the outlet is mainly composite scale, which is formed by the fine particles and inorganic scale with heavy oil. In addition, the water sensitivity with clay leads to the decrease in permeability. This work provides a theoretical and scientific basis for the development of technology to effectively prevent reservoir blockage.