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Collaborating Authors
Results
Study on the Drilling Fluid Flow Rate Allowable Range in Offshore Drilling Considering the Extended-Reach Limit
Li, Xin (China University of Petroleum) | Gao, Deli (China University of Petroleum) | Tan, Leichuan (China University of Petroleum) | Zhang, Hui (China University of Petroleum) | Chen, Xuyue (China University of Petroleum) | Zhou, Yingcao (CNPC Drilling Research Institute)
Abstract Offshore drilling has the characteristics of high risk investment, increasing the difficulties of offshore drilling design. Conventional offshore drilling fluid flow rate design method fail to consider the effects of extended-reach limit in offshore drilling. As a result, the extended-reach well (ERW) may unable to reach to the designed well trajectory length, causing potential safety hazards. Therefore, there exist a drilling fluid flow rate allowable range (DFFRAR) in offshore ERW. In this study, considering the dynamic pressure balance of bottom hole and drilling pump's rated pressure and rated power, coupled with the needs of hole cleaning, four constraint conditions of DFFRAR and corresponding DFFRAR prediction model are proposed. The predicted DFFRAR of offshore ERW must satisfy these constraint conditions simultaneously. In the end, an ERW in South China Sea is analyzed, and the well's DFFRAR is also determined. Furthermore, some optimization measures are also put forward to obtain wider DFFRAR. The results of case study show that the DFFRAR of offshore ERW in South China Sea ranges from 31.1 L/s to 35.7 L/s when the designed well trajectory length is 3243 m. In addition, the DFFRAR becomes narrower with the increase in designed well trajectory length and ROP. In contrast, the DFFRAR becomes wider with the increase in rated pressure of drilling pump and fracture pressure of drilled formation. Moreover, the window of DFFRAR will be closed if one of these constraint conditions is not satisfied. A wider DFFRAR is conductive to the offshore drilling safety. It is necessary to obtain wider DFFRAR as much as possible by taking optimization measures. This work provides a practical tool for determining the offshore ERW's DFFRAR and achieving wider DFFRAR in order to improve the drilling efficiency and obtain good economic benefits in marine environment.
Abstract Cuttings accumulation is a major challenge in horizontal gas drilling, it may lead to accidents such as wellbore plugging and pipe sticking. The newly-developed jet mill bit (JMB) may overcome the challenge fundamentally by comminuting cuttings into dusk-like scale right after the cuttings are generated. In this paper, the JMB is investigated as an innovative method to improve cuttings carrying capacity in horizontal gas drilling. It presents the JMB's working principle and cuttings-comminuting mechanism, and explains why it is developed based on the analysis of cuttings carrying capacity in horizontal gas drilling. Analysis using field data in the published article demonstrates that the max cuttings that can be carried by the annular gas are dust-like and much smaller than the initial cuttings size in the high angle build section and horizontal sections, it needs several times as much gas injection volume as the current annular gas injection volume to eliminate cuttings accumulation. JMB can comminute cuttings in dusk-like scale and may eliminate cuttings accumulation fundamentally, meanwhile drilling complications such as near bit hole washout, hole deviation, and ice-balling (frozen) of bit can also be avoided in horizontal gas drilling.
- North America > United States (0.46)
- Asia > China (0.29)
- Research Report (0.47)
- Overview > Innovation (0.35)
- North America > United States > Oklahoma > Arkoma Basin > Fayetteville Shale Formation (0.99)
- North America > United States > Arkansas > Arkoma Basin > Fayetteville Shale Formation (0.99)
Abstract Mega-extended-reach wells (MERWs) can be drilled from one platform to develop the remote surrounding satellite oil & gas reservoirs in deepwater. Though the platform is located in shallow water, some MERWs can be targeted the reservoirs in deepwater. In mega-extended-reach drilling (MERD) to deepwater target, some challenges that may be faced are the presence of low temperature, typically weak overburden sediments, unconsolidated formations and a small sedimentary coverage above the reservoir. This results in a narrow safe mud weight window (SMWW) and a limited well depth for MERD operation. In this work, considering the pressure balance of bottom hole including the thermal and seepage effects, a method for predicting the maximum allowable well depth (MAMD) of MERD to deepwater target is presented. Meanwhile the factors affecting the MAMD of MERD to deepwater target are also investigated. The study shows that seepage significantly affects the MAMD of MERD to deepwater target while the thermal's effect is not very obvious, seepage turns out to significantly decrease the MAMD whereas heating the formation is found to be helpful in extending the MAMD. It also shows that the predicted MAMD of MERD turns out to be obvious anisotropy, drilling in the direction of minimum horizontal in-situ stress in the formation is prone to attain a wider SMWW and a longer MAMD than other directions. Moreover, for a given target zone, the MERD with a horizontal bottom hole has a much longer MAMD than that of MERD with an inclined bottom hole, and the MAMD can also be effectively increased by reducing the annular pressure loss. This work provides a practical tool for enhancing the design of MERWs to develop the remote satellite oil & gas reservoirs in deepwater.
- Asia (0.69)
- Europe > Norway > Norwegian Sea (0.45)