a b s t r a c tCarbon dioxide enhanced oil recovery (CO 2 -EOR) and sequestration in depleted oil reservoirs is a plausible option for utilizing anthropogenic CO 2 to increase oil production while storing CO 2 underground. Evaluation of the storage resources and cost of potential CO 2 -EOR projects is an essential step before the commencement of large-scale deployment of such activities. In this paper, a hybrid techno-economic evaluation method, including a performance model and cost model for onshore CO 2 -EOR projects, has been developed based on previous studies. Total 296 onshore oil fields, accounting for about 70% of total mature onshore oil fields in China, were evaluated by the techno-economic method. The key findings of this study are summarized as follows:(1) deterministic analysis shows there are approximately 1.1 billion tons (7.7 billion barrels) of incremental crude oil and 2.2 billion tons CO 2 storage resource for onshore CO 2 -EOR at net positive revenue within the Chinese oil fields reviewed under the given operating strategy and economic assumptions. (2) Sensitivity study highlights that the cumulative oil production and cumulative CO 2 storage resource are very sensitive to crude oil price, CO 2 cost, project lifetime, discount rate and tax policy. High oil price, short project lifetime, low discount rate, low CO 2 cost, and low tax policy can greatly increase the net income of the oil enterprise, incremental oil recovery and CO 2 storage resource.(3) From this techno-economic evaluation, the major barriers to large-scale deployment of CO 2 -EOR include complex geological conditions, low API of crude oil, high tax policy, and lack of incentives for the CO 2 -EOR project.

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China oil and gas operators are more and more engaged in the exploration and production of much deeper oil and gas prospects that are pushing the boundaries and limits of the traditional drill stem. A high number of ultra-deep wells (above 7 000 meters) are being drilled in the Xinjiang area. In this part of China, there is a need to improve the hydraulic and mechanical performances of the drilling tubulars used in both large and slim hole size intervals. A key feature in these products’ performances is the rotary shouldered connection (RSC). API RSC typically requires larger profiled tool joints to provide acceptable torque and tension capacity. However, this increase s pressure losses and restricts fishability. Double shoulder connection (DSC) technology has been successfully used to address this mutually exclusive need for both torque and hydraulics. CNPC has greatly benefited from their decision to use a first generation double shoulder connection (1st gen DSC) on various sizes of drilling tubulars to successfully drill the deepest exploration well in the Jungar basin as well as numerous exploration and production wells in the Tarim basin. This paper will first describe the DSC technology, how it contributes to the improved drilling performance, and will present supportive case histories. The 1st gen DSC performed very successfully. Looking ahead, deeper prospects are on the horizon and further enhancements in drill pipe and DSC technology will be necessary. Prospective future options will also be discussed in this paper.