Hydraulic fracturing technology is widely used to facilitate and enhance the recovery process from oil and gas reservoirs. Much worldwide experience has been gained in stimulating conventional and shale oil reservoirs; however achieving good stimulation results in mature (depleted) oilfields with moderate permeability can be challenging and can easily fall below expectations for a variety of reasons. To narrow the gap between expected results and actual well performance after a successful fracturing treatment it is very important to understand the reservoir characteristics and the actual reservoir potential. Despite the common opinion that stimulating mature, depleted wells is unprofitable, experience shows that stimulating such wells can still result in substantial and profitable production increases. Twenty hydraulic fracturing treatments performed on wells in a mature onshore oil field wells in Myanmar, in south-east Asia have shown significant increases in initial incremental oil production rate—on average by a factor of two, which was still below the expectations. The treatments have effectively increased cumulative production and arrested exponential decline by +62% per annum. The result is a flatter production profile and has higher sustained oil production rates. This paper discusses the challenges seen and the results obtained utilizing hydraulic fracture stimulation in a mature oilfield. This case shows the importance of a proper candidate selection method, which has contributed to successful stimulation and improved oil recovery in this case.

Summary Hydraulic-fracturing technology is widely used to facilitate and enhance the recovery process from oil and gas reservoirs. Much worldwide experience has been gained in stimulating conventional and shale oil reservoirs; however, achieving good stimulation results in mature (depleted) oil fields with moderate permeability can be challenging and results can easily fall below expectations for a variety of reasons. To narrow the gap between expected results and actual well performance after a successful fracturing treatment, it is very important to understand the reservoir characteristics and the actual reservoir potential. Despite the common opinion that stimulating mature, depleted wells is unprofitable, experience shows that stimulating such wells can still result in substantial and profitable production increases. Twenty hydraulic-fracturing treatments were performed on wells in a mature onshore oil field in Myanmar, in Southeast Asia. These wells had never been fracture stimulated in the past, because of the moderate-to-high permeability of the reservoir. The stimulated wells have shown significant increases in initial incremental oil-production rate—on average, by a factor of two, which was still below the expectations. The treatments have effectively increased cumulative production and added to reserves. At the time of writing, the daily production rate from the 20 wells is actually increasing, rather than declining. This is likely caused by some kind of cleanup effect related to fracture stimulation in this highly depleted reservoir. This paper discusses the challenges seen and the results obtained using hydraulic-fracture stimulation in a mature oil field. This case shows the importance of a proper candidate-selection method, which has contributed to successful stimulation and has improved oil recovery in this case.