1.1 Problem Statement
Formation damage refers to the impairment of the permeability of petroleum bearing formations by various adverse processes. Formation damage is an undesirable operational and economic problem that can occur in many phases of field development including drilling, completion, workover, production, stimulation, waterflooding and enhanced oil recovery. In fact, it is among the major causes of a well productivity reduction in petroleum reservoir. Proper understanding of the factors causing these damages is therefore of utmost important. Formation damage indicators include permeability impairment, skin damage and decrease of well performance.
Formation damage can be caused by factor such as fine particle transportation in porous media. Fines enter the formation as suspensions during drilling and completion operations. They can also be generated due to fluid-fluid and fluid-rock interactions. When they enter the formation, they get entrapped in the pore openings, fill and plug the pore spaces of the formation. Sedimentary rocks also contain loosely attached fines. When injection fluids are incompatible with formation fluids, these fines can be released from the rock surface, migrate and plug at pore constrictions. The end result is severe permeability reduction.
It is therefore essential to develop experimental and analytical methods for understanding and preventing and/or controlling formation damage in oil and gas bearing formations (Energy Highlights, 1990). The laboratory experiments are important steps in reaching understanding of the physical basis of formation damage phenomena. From this experimental basis realistic models which allow extrapolation outside the scaleable range may be constructed (Energy Highlights, 1990). These efforts are necessary to develop and verify accurate mathematical models and computer simulators that can be used for predicting and determining strategies to avoid and/ or mitigate formation damage in petroleum reservoirs (Civan, 1994).
Most of the previous work on formation damage dealt with single-phase flow of fluids or filtrates. Several models have been developed that characterized fines migration in single-phase flow. In reality, multiphase flow is commonly encountered in petroleum bearing formations than single-phase flow. There is scarce information in the literature about formation damage during multiphase flow. The present work seeks to develop a mathematical simulation model for formation damage due to chemical precipitation and particulate processes in the presence of oil and water.
The objectives of this work are as follows:
1. To develop a mathematical model for the simulation of formation damage due to chemical precipitation and particulate processes in two-phase flow of oil and water.
2. To obtain the numerical simulation of the developed model.
3. To compare the results obtained from the simulation with real experimental data available in the literature.