Application of Self-Conforming Well Stimulation Technology in Oil and Gas Fields - Fundamentals and Case Histories

Summary The primary aim of the research project was to develop an efficient technology to control excessive water production in gas and oil wells. As a novelty, water sensitive petroleum-based solutions were developed, which spontaneously form extremely high viscosity barrier under reservoir conditions when contacting with water. Thus, application of that reservoir conformance control technique in fields becomes independent of placement methods even in case of bullhead treatments. After detailed fundamental and applied studies the technology was deemed matured to test under field conditions. Until now, more than 16 well treatments had been carried out including both oil and gas producers. The project is still running in a gas capped oil reservoirs of the largest stacked hydrocarbon field Algyő, Hungary. The detrimental (higher than 100 m3/d) water production was the primary factor selecting the target wells to be treated. Evaluating the field results, it was concluded that the treatments prove a multifunctional mechanism. The water production in some wells dropped significantly (from 120 m3/d to less than 30 m3/d); meanwhile the gas production remained unchained. In case of some wells, the water production remained unchained, however, the gas production tripled. Surprisingly, all treated gas producers operating in gas capped oil fields, which never produced liquid hydrocarbons started to produce substantial amount of oil (between 10% and 75% oil in net fluid rate). These positive results can be attributed to three different reasons: effective barrier formation against water influx, reducing skin factor caused by formation damage, and opening new flow paths from entrapped oil bodies existing below the gas cap. Thus, the treatment technology was qualified as a “multifunctional well stimulation” contrast to the original term of “water shutoff” method. Based on the encouraging field results the technology became one of the strategic projects of the company in the coming years until 2020.