Abstract
A benchmarking study on 43 steamflood of light/medium crude oils was performed, to find attractive reservoir characteristics and successful operational practices that are used worldwide. More than 30 successful projects were analyzed and summarized in a database, which included reservoir properties, best operational practices and results obtained. On average, an incremental oil recovery of 19% OOIP was obtained by steamflooding, during a project lifetime of up to seven years.
Based on the successful project characteristics, we developed a model to rank potential reservoirs. Reservoir data were analyzed using standard statistical methods for properties, such as: API gravity, initial oil saturation, reservoir temperature, porosity, initial pressure, depth, net pay, viscosity at reservoir condition, initial (at the beginning of steamdrive)-bubble pressure ratio and average permeability. The statistical model ranked the properties on a standardized score scale. A predicted score close to one hundred indicates a high probability of success. Supported by this numerical model, we selected the La Salina reservoir (La Rosa Formation, Lake Maracaibo, Western Venezuela) as a potentially successful reservoir to apply steamflood technology.
In addition, unsuccessful projects from two different reservoirs (the Naval Petroleum Reserve No. 1, and Buena Vista Hills, both in the USA) were analyzed, to understand the reasons for failure. Several reasons were identified, such as: poor reservoir characterization, thief zones and carbon dioxide formation by decomposition of reservoir minerals.
