Abstract
Historically, stimulation treatments made on water injector wells from a mature oil field located in the Middle Magdalena Valley in Colombia, have not been successful. This study is a comprehensive methodology of formation damage analysis performed throughdamage modeling, reservoir and water injected fluids characterization and specialized laboratory tests, to guarantee an adequate well candidate selection methodology, by identifying and quantifying the formation damage mechanisms (fines mobilization, solids invasion, emulsion formation) to achieve an optimum stimulation treatment selection.
In order to identify the formation damage mechanism currently affecting the injector wells in the field, which is believed was induced in this sensitive reservoir during the drilling/completion operations and their initial water injection stage which was developed and implemented for the first time by the operator thirty years ago, the following process was performed.
Initially, all the information available was collected and analyzed. Reservoir fluids and drilling/completion fluids compatibility tests were conducted to identify any incompatibilities; solids samples found plugging the string injection ports of the injector wells, were recovered and characterized. Cores from representative zones of the target zones were taken in order to check the mineralogy and review the damage. The possibility of mineral scaling presence, caused by the mixture of injection and formation water at down-hole conditions was evaluated, using specialized software. Then, all the data collected from the previous analysis, was used to generate a comprehensive formation damage model. The use of a geochemical simulator software which integrates numerical simulations, specialized reservoir studies, nodal analysis, mineral/organic studies and souring studies, allowed to identify and quantify the weight of each damage parameter. A 3D simulation of some of the parameters will be presented.
Having identified the induced formation damage parameters, a complete set of laboratory tests were planned and conducted to diagnose, identify and evaluate the best stimulation treatment to dissolve and mitigate the damage. An appraisal of the impact of formation/injection water salinity in the formation was done, as well as the test of formation sensibility to the fines dissolution treatments, mainly performed through the analysis of retain permeability, critical velocity and effluents, acquired in the core flow tests.
This paper will present the complete methodology and the field results of the successful application on a set of injector wells, which regain the desired water injection rate exceeding the expectations and contacting new zones to drain new oil reserves.
