ABSTRACT

Particle invasion and fines migration are among the major factors causing formation damage. Extensive studies of formation damage in laboratory and several modeling efforts for prediction of formation damage have been reported in the literature. However, a satisfactory model to simulate the near-wellbore formation damage in field conditions is still not available. In this paper, the linear flow core-scale model presented previously by Liu and Civan is converted into a radial flow field-scale model to simulate the formation damage near wellbore regions in actual field conditions. The radial flow field-scale model utilizes the values of model parameters obtained by a model assisted analysis of the laboratory core tests to determine the temporal and spatial variation of formation damage and the associated skin factor. Simulation results indicate that the overbalance pressure of drilling fluids is an important factor for formation damage control and that the formation damage due to constant-pressure mud filtration is less severe in two-phase flow of oil and water than single-phase flow of water in the formation.

INTRODUCTION

Formation damage occurs in almost every field operation. It is an adverse and complicated phenomenon caused by particle invasion, formation fines migration, chemical precipitation, organic deposition, and pore deformation or collapse. The production performance of a well is strongly affected by the magnitude of damage in the near-wellbore formations. Searching for methods to reduce the cost of formation damage is of continuing interest to the petroleum industry. Formation damage near wellbore can be determined by well testing techniques. However, these techniques can only provide the skin factor as an overall measure of formation damage, but they do not reveal any insight into the temporal and spatial development and causes of the damage for the assessment and control of formation damage.

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