Study of Carbonate Reservoirs Examines Fines Migration in CO2-Saturated-Brine Flow

摘要

A high-carbon-dioxide(CO2)carbonate gas field offshore Sarawak,Malaysia,is scheduled for development.Reservoirs in this region have an average clay content of 8%;more than 50% of this clay content is migratory illite,and 15% is migratory kaolinite.Therefore,fines migration exacerbated by this low-permeability rock becomes a potential production and injection problem.A study was conducted involving rock mineralogy and dynamic flow to evaluate factors contributing to potential fines-migration damage within the production and injection interval.Migration of fines is associated with oil and gas production in sandstones as well as carbonate reservoirs.Fine particles located on the surface of rock grains are affected by adhesion,drag,and electrostatic and gravitational forces.Drag and lifting forces detach the particle,whereas adhesion,electrostatic,and gravitational forces press the particle to the surface.Generally,the main sources of movable fine particles in sandstone reservoirs are kaolinite and illite clays.Kaolinite particles are flat plates usually stacked in the form of booklets.The surface area of clay minerals,for example,typically is large because of their structure and small size and is more reactive and prone to mobilization and migration.