Deep Profile Control Agent Developed

Today in our country most of oilfields using water injection have stepped into high-aquifer stage, and therefore it is important to deal with the deep stratum. A new kind of nonpoisonous in-depth profile controlling agent, which is delaying crosslinking weak gel. It has the characteristics of low polymer and crosslinker concentration, inexpensive charge and controllable gelling time, so it is suitable for large volume treatment to improve the volumetric sweep efficiency of water, modify the water profile and enhance the recovery ratio.In this paper through three ameliorations to the prescription of the in-depth profile controlling agent, we get the gel whose intensity has developed and the gelling time has shortened, its stability has also enhanced and it can be applied to the broader range. Ultimately the agent includes the polymer, organic crosslinker, the second crosslinker and stabilizer etc. The main evaluation of performance is by means of the variety of viscosity and the control of gelling time, and we ascertain the concentration range of additives and the optimal dose. The rule of the weak gel was investigated. These factors include polymer(types, molecular weight, concentration and hydrolysis degree), crosslinker(concentration, the concentration ratio of aluminium and ligand of the organic crosslinker and age of its solution), the concentration ratio of polymer and organic crosslinker, the concentration of deoxidant, temperature, PH, shearing state, solution salinity, and so on. The results of core flooding experiment and the study of the propagation about the weak gel show that the agent has a high blocking rate and good selection which can modify the water profile well.By investigating the shape of the organic crosslinker and the reaction tothe large molecule chain, we probe into the mechanism of the gel. Then the electron microscope scan experiment have validated the mechanism directly . The photos show that the gel structure of the gel is very strong and has many layers reticulation configurations.The result of static adsorption and dynamic retention of polymer in the porous media shows that the dynamic retention is much smaller than the static adsorption. The whole amount of adsorption and retention is not much high which is in the range of the error.