Integrated analysis of the water injection process in the Casabe field: a strategy to reduce uncertainty and improve recovery efficiency

Abstract

The Casabe Field is formed by an asymmetric anticline structure with moderate dip to the east, affected by transpression faults that involve sedimentary sequences from the Cretaceous and Paleogene time. As a consequence, normal and inverse faults occurred that define 8 operating blocks in the field. The high heterogeneity of unconsolidated deposits produced as a whole, the limited continuity of the area of the deposits and the unfavorable mobility relationships are highlighted as relevant characteristics. These conditions motivated the technical team of the field to carry out integrated and multidisciplinary analyzes that include studies of geology,
deposits and underground engineering, validated with the operational experience obtained in the field, in order to efficiently exploit the hydrocarbons of each of the 23 production layers.

This integrated analysis incorporates changes in the volumes of water injection by sand based on the remaining volumes of oil, calculated from volumetric and displacement efficiencies and hydraulic connectivity studies. From these volumes, incremental production forecasts were defined using fractional flow curves. In the same way, injection profiles were also determined that generate a balance condition in the system. All this, in order to increase the recovery factor in the field, improve the use of injection water and decrease the failure rate related to imbalances in the production-injection system. The results until date indicate that a 25% reduction in the failure rate has been obtained in the study areas, a 21% increase in production, a reversal of the field decline trend from 15% to 7 % and a 30% reduction in costs associated with energy and chemical consumption for water treatment.