The success of the program required cooperation among a wide range of exploration professionals, from geologists seeking out untapped rock to fracturing engineers considering the best way to divert fluid so it reached the targeted areas. Refracturing could open production pathways where there has been “degradation of fracture conductivity over time.” Some aimed at hitting newer reservoir rock in higher-pressure zones, others were designed to improve the output from older reservoir sections in which flow assurance was often a problem. A cement bond log estimating that 95% of the cement is sound leaves enough room for a channel that can divert fluid and undercut the effectiveness of the fracturing work. The condition of the steel casing and cement around it is also critical. He said a study showed wells in the Permian in which 30% of the reserves had been bypassed. At the top of the list: Are there significant volumes of good quality reservoir that have not been tapped. Based on the slides shown during Babaniyazov’s presentation, screening required answering many questions. The answer to the question was complicated. Industry reports on refracturing tend to focus on successes, with little data available about the ones that had failed and the causes. There was limited industry experience to draw on. “USD 30/bbl is not the same as USD 50 bbl.”ĬonocoPhillips’ campaign was started because it had a significant number of wells dating back as far as the 1960s, when production had dwindled to the level at which the company needed to spend to increase the output or plug and abandon the wells.Ī way was lacking to identify which of the wells would be candidates, and rank which offered the greatest potential payoff. “When I was involved, it was USD 50/bbl and now it is what, 29 a barrel?” he said during a presentation in mid-January. The price collapse has put the program on hold at a time when spending has been slashed, and the outlook is uncertain because prices for oil and services are so hard to predict. While the latter options cost more, they also offer higher potential gains. The cost varied because the nature of the work ranges from acidizing to refracturing or deepening the well. “With the growing numbers of aging wellbores, rework in the existing zones such as refracturing helps to reduce temporarily abandoned well counts, increase production rates, and often reserves,” he said, adding, “the ‘rework inventory’ remains high and economically attractive for Permian Basin operators.”Ī campaign in 20 covering more than 70 wells yielded an 80% success rate, which Babaniyazov defined as a production gain that allowed payback on the investment within 6 months to a year.
The point was that there is money to be made on the oil left behind in reservoir rock that is of far higher quality than the unconventional rock layers, which have gotten far more attention and investment in recent years. The wells were in conventional reservoirs in the Permian Basin, some dating back to the mid-century years he referred to as when far fewer wells were fractured but a significant number were refractured, often multiple times. That statistic came from a recent presentation by Anton Babaniyazov, a staff production engineer for ConocoPhillips, who used it to begin a talk for the SPE Gulf Coast Section’s Permian Basin Study Group about a successful fracturing campaign in west Texas. There has been a lot of talk about refracturing recently, but the percentage of wells fractured more than once is a small fraction of the 35% rate from the 1950s to 1970s.
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