Abstract
Poor well performance due to permeability and conductivity damage can often be attributed to unbroken gel residue or inadequately reduced filtercake on formation faces. These forms of polymeric damage can negatively impact production rates by restricting the flow of oil or gas from the formation. Remedial treatments have been applied to wells exhibiting this type of damage using acids, oxidizers and enzymes. These removal treatments, when applied to accurately diagnosed polymer damaged wells and effective breaker systems are utilized, have shown to increase well production dramatically. However, polymer damage is only one of many factors that might be responsible for impeding optimum hydrocarbon flow. Therefore, the key to the success of a removal treatment is proper evaluation for polymeric damage when selecting a treatment candidate.
An improved flow back analysis has been recently introduced as a series of tests for polymer damage and for the evaluation of treatment load recovery. The testing procedures involved in that analysis can also be applied in candidate selection for remedial treatments and for monitoring the resulting clean up progress. Samples are analyzed before and after the treatment to determine total carbohydrate content, molecular weight distributions and the standard pH and viscosity measurements. The utilization of this improved analysis can assist in the selection of appropriate candidates and further direct treatment design. Several case histories on low performance wells are presented and include laboratory data to demonstrate candidate selection. Treatments with enzymes were used and detailed results are provided to evaluate the amount of polymer recovered. This paper also presents a guideline for use in the selection of candidates for remedial treatments.
