Paper: Injection Well Cleanouts In The Iatan East Howard Field

The Iatan East Howard Field is located in eastern Howard County, Texas. Production is commingled from the San Andres, San Angelo and Clearfork zones. Pressure support in the field is provided by waterflood. Injectivity into these zones was poor due to the buildup of iron sulfide and biomass. Several methods were used to cleanup this buildup. The first method used was to cleanout the wellbores with 15% acid and 14% sodium hypochlorite (bleach), utilizing a coiled tubing unit. The second method was to pump bleach and acid into the injection system, which would in turn be pumped down the wells. The third method was to cleanout both the surface and downhole lines with 3000 parts per million (ppm) chlorine dioxide (CL02) and 15% NEFE acid. The relative benefits and costs of these three methods is discussed. This work was performed when ARC0 Oil and Gas (ARCO) operated the properties. In the fourth quarter of 1992, Anadarko purchased APCO's interest in the properties. It is not the objective of this paper to discuss the chemistries and chemical reactions involved with these methods. Those can be found in numerous places in the literature. The objective is to communicate the procedures involved, the costs, and the benefits.