Don M. Everett

The Succesful Evolution of Anton Irish Conformance Efforts

The Anton Irish field was discovered in 1945, unitized in 1950 for a produced gas pressure maintenance project and converted to a waterflood in 1969. In 1997 CO2 flooding began and currently accounts for about 85% of the unit production. Presently, the entire field produces around 6,500 BOPD; 36.5 MMCFPD of recycled CO2, and 69,200 BWPD. Over the years of flooding, various conformance problems have been identified and many attempts have been made to address these problems with limited to no success. In 2003 a new program was initiated to re-evaluate the problems and design better solutions. This paper will outline the diagnostic efforts that were undertaken, discuss the basic findings of that effort, review the resulting solutions that were designed to resolve these problems, and show the results of this work. Basic Problem / Justification For many years the rapid breakthrough of the displacing fluid whether it was water or CO2 has been recognized as a severe problem in the Anton Irish Field. This rapid breakthrough and excess cycling of CO2 in the Anton Irish Clearfork flood has led to numerous wells being shut in due to limited processing capacity at the gas plant. In addition wells that had previously produced at relatively high oil rates became uncompetitive due to this excess gas production. Thus, in order to recover reserves from these areas, a solution needed to be found to address these excess cycling problems. A key complicating factor to deal with at Anton, is that almost all wells have open hole completions. This creates additional diagnostic problems as it is difficult to get to bottom with wireline on most injectors which prevents good injection profile data.