Modeling the Effect of Oilfield Sulphate Scales from Productivity Index

Adesina S. Fadairo, Olugbenga Falode, Olusegun Omole, and Gbadegesin Adeyemi
Petroleum Engineering, Covenant University, Ota, Nigeria

Scaling phenomenon is a major problem in water flooding where injected and formation waters are incompatible and their mixing causing salt precipitation. The phenomenon results in precipitation and accumulation of oilfield scale around the well bore after the water breakthrough at reduced reservoir pressure. The process results in formation damage and influence reservoir performance, pose serious injectivity and productivity problems during water flooding project. Several models have been developed to predict oilfield scales formation and their effect on deliverability of the reservoir to aid in planning appropriate injection water programme.

In this study, an analytical model has been developed for predicting productivity of reservoir with incidence of scale deposition in the vicinity of the well bore caused by mixing of incompatible waters. The model assumed steady state flow of oil and water, average scale concentration in the reservoir and exponential shape for formation damage function in water flooded reservoirs with incidence of scale deposition in the vicinity of the well bore caused by mixing of incompatible waters.

Conditions such as degree of super saturation, composition variation, ionic strengths, pressure and temperature control the quantity of crystals precipitated; while flow rate, pressure draw down, concentration variation, formation properties, fluid properties control the build up rate of the solid scale and productivity impairment during water flooding.

AAPG International Conference and Exhibition, Cape Town, South Africa 2008 © AAPG Search and Discovery