Remediating Condensate-Banking in Both Fractured and Unfractured Wells

Abstract

The undesirable impact of condensate-banking on wellbore productivity and recovery factors in gas condensate systems has been extremely well researched and documented. Although surprisingly, likely due to a mentality of wishful thinking, it is often almost completely ignored or its impact at least supressed in terms of ensuring it is adequately addressed in a Field Development Plan (FDP). While the more enlightened operators will apply gas-cycling or more often massive hydraulic fracturing to address this, ultimately the condensate-banking effect will eventually dominate the reservoir behaviour as the pore-pressure falls below dew-point and the inevitable phase and saturation behaviours change. As a result, the oil & gas industry has toyed with any number of approaches to dealing with the resulting loss of productivity, through various intervention approaches. These techniques have included the use of lean gas injection, re-fracturing operations, or alternative stimulation approaches; although the lack of published successful case histories and widespread application indicates that the success of such methods has been limited at best. In order to address this effect, a highly impactful approach was developed, tested and operationally confirmed using infused (aerosol) deployed chemistry within lean gas solutions. Combining the effects of optimal coverage, penetration, sustainability, and contact with the system which resulted in significant uplift in laboratory and field measured EUR, RF and remediation impact. The approach has been developed over some years, in response to the loss of productivity and ultimate recovery-factor in a trend of deep, hot and extensive retrograde gas-condensate fields in the Eastern cordillera of the Andes mountains of Colombia. Since initial development, this unique chemical-in-gas dispersion approach, referred to as gas infused technology, has continued to be refined, developed further and applied with increasing success for the treatment of condensate banking, water-blockage, fracture clean-up, and asphaltene deposition. The paper will demonstrate a number of field examples, combined with prior laboratory testing and chemistry selection and refinement, to demonstrate that the infused gas-droplets solution is both superior to and more impactful than other alternatives where they may exist. This paper presents a unique and novel combination of chemical stimulation techniques, to alleviate gas-condensate banking; by combining chemical technology with gas borne delivery of engineered particle sizing deep into damaged formations. Deployed in hydraulically fractured or also non-fractured wellbore environments, the resulting impact on gas-condensate reservoir performance has resulted in significantly enhanced well and reservoir economics. An entirely new form of stimulation approach, Chemically Infused Gas (CIG), potentially opens up a whole new branch of gas borne stimulation which has yet to be fully investigated and appreciated.