Comprehensive treatment technologies for the stripped and deficient wells of Bohai heavy oil field in high water cut stage

S Oilfield is a typical waterflooding heavy oil field in Bohai Sea, and by now, it has stepped into the two-high stage (high degree of reserve recovery and high water cut). With the rise of water cut, the number of stripped and deficient wells increases year after year, which seriously impacts the development effect of S Oilfield. Based on the geological and development characteristics of S Oilfield, this paper analyzed the causes of stripped and deficient wells from the aspects of remaining oil, sandbody development, reservoir heterogeneity, injection-production relationship, drilling & completion contamination and wellbore integrity. In addition, the stripped and deficient wells were classified. And based on the classification, the corresponding treatment countermeasures were studied, and the treatment strategies of “areal zoning, vertical layering, classification based research, and simultaneous treatment and potential tapping adjustment” were developed, so as to give full play to the oilfield potential and improve the economic benefit to the utmost. Based on the research and application of stripped and deficient well treatment technologies in S Oilfield in the last three years, a series of technologies have been developed, including high water cut sandbody potential tapping, thin bed potential tapping, high-water-cut horizontal well productivity evaluation, injection/production well pattern adjustment and control, and potential reserve evaluation, which have successfully guided the treatment of 51 stripped and deficient wells in S Oilfield, achieving new proved reserves of 300×10⁴ m³. 33 stripped and deficient wells were treated during 2017-2019, and the daily oil increment was 1 200 m³ in July 2019. It is predicted that the cumulative oil increment by the end of development stage will be nearly 240×10⁴ m³ and the recovery factor will be increased by about 1%, indicating remarkable treatment results of stripped and deficient wells. The research and application of these comprehensive stripped and deficient treatment technologies is of certain guidance and reference significance to the treatment of stripped and deficient wells of offshore heavy oil fields in high water cut stage.