A few wells, from a major Western India on-shore oil field, are either on the verge of being shut-in or have already been abandoned, due to excessive water-cut (WCT) levels. Low injectivity and extreme temperatures (149°C) make it difficult for water shut-off by conventional polymer gel injection. A water thin monomer-based in-situ gelation system has been developed and successfully tried in one of the wells that ceased production due to 100% WCT. The average production of 420 b/d with less than 1% WCT, in the Ist year of production hack in 1996, declined to less than 8 b/d (with 98% WCT) prior to shut-in in year 2002. A rise in the oil-water contact (OWC) level in combination with a coning effect was diagnosed as a possible cause of the high WCT that was later controlled by a newly developed gelant treatment. In fact, the average post-treatment production for the first three months was nearly 200 b/d. Thereafter, production gradually stabilized in the neighborhood of 115 b/d with a WCT of 48%. Cheap chemicals and a fast treatment method have resulted in a payback time span of 5 days and made an additional profit of 0.6 million US $. The water shut-off job resulted in an impressive commercial success; technical success, however, was less than satisfactory due to the fact that, in spite of using a water-thin monomeric solution, only 40% of the designed volume could be injected due to low injectivity resulting in an abnormal pressure buildup. In addition to the gel development and treatment experiences, this article describes in detail the results of further lab investigations carried out to identify the possible reasons causing injection failure.
|Number of pages||3|
|Specialist publication||Oil Gas European Magazine|
|Publication status||Published - Dec 2006|
ASJC Scopus subject areas
- Energy Engineering and Power Technology
- Fuel Technology