ABSTRACT
Formation Damage resulting from the migration of small, mobile mineral particles within hydrocarbon producing formations has been, and continues to be a major concern of drilling and production engineers. The flow rate at which these small, usually colloidal, particles begin to dislodge and move within a formation is referred to as the critical flow rate.
Many factors can influence the migration of fines within a producing formation: mineral composition, size and shape; pore throat size and distribution; relative fluid saturations; particle wettability; viscosity of the mobile fluid phase; fluid interfacial tension; production rate; and chemical alteration by drilling and completion fluids can affect the mobility of mineral species responsible for formation damage from in situ fines migration. A novel approach for the analysis and quantification of formation damage resulting from fines migration is described in this paper. The analysis is routinely performed on core plugs from whole core, rotary sidewall cores, and percussion sidewall cores. The technique described employs industry accepted practices for the measurement of single and multiphase permeability of core samples at reservoir conditions, as well as a novel experimental methodology and data processing technique for critical rate determination. A baseline permeability is established at a very low production rate. The rate is subsequently increased in a step wise fashion, returning to the established base rate after every consecutive rate increase. Experimentally derived flow rate and permeability data are converted to bottom hole and wellhead production rates using completion data and well geometry.
The technique described in this paper is used successfully to augment production efforts in several producing formations by integrating the data obtained from flow studies with X-ray diffraction, scanning electron microscopy, and petrographic analysis.
By imparting the ability to vary drilling and completion procedures while under simulated reservoir conditions in the laboratory, this analytical technique can reduce the risk of formation damage at all stages of well operations.
