Use of the Continuous Circulation System on the Kvitebjørn Field
Abstract: The reasons behind Statoil choosing to include continuous circulation in HPHT Managed Pressure Drilling operations in the Kvitebjørn Field in the North Sea are explained. The paper will also discuss the preparations for the operation and the equipment and manpower required to enable the Continuous Circulation System to be installed and operated on the platform. Results recorded by the drilling team during the drilling period are described. Reference is also made to other applications of the Continuous Circulat… Show more
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Cited by 5 publications
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Verification of Downhole Choke Technology in a Simulator Using Data from a North Sea Well
The most important contributer to Improved Oil Recovery (IOR) on mature fields is drilling of infill wells. Managed Pressure Drilling (MPD) and Continuous Circulation System (CCS) techniques can be used for improved control of bottomhole pressure when drilling wells in depleted fields with narrow pressure windows, but rig heave is a challenge when drilling from floating drilling units. Rig heave, caused by sea waves, induces pressure oscillations downhole that may exceed the operational pressure window. These oscillations are called "surge & swab" and occur both during tripping in and out of hole as well as during drill pipe connections, when the topside heave compensation system used during drilling is disabled because the drill pipe is put in slips. Downhole choking was introduced as a method to reduce downhole pressure oscillations induced by the rig heave and the concept was tested in laboratory scale and using computer simulations (Kvernland et al., 2018). The simulations were perfomed using a purpose-developed software which utilizes such input variables as wave height, pump flow, drill pipe movements, rig characteristic (RAO), drilling fluid properties as well as well design, drill pipe and Bottom Hole Assembly (BHA) data to simulate downhole pressure, induced by rig heave. The simulator is designed to model dynamic interactions between the drilling fluid and the drill string in a rigorous manner, which gives it ability to accurately predict fast downhole changes, such as ones induced by ocean waves. This paper gives an overview of the surge & swab simulator, describing its capabilities and limitations. Data from drilling of a North Sea well is then used to validate the simulations made using the software. The well, used as example in this paper, was drilled conventionally from a floating rig. The downhole pressure variations recorded during three different drill pipe connections are compared with simulated downhole pressure. The simulations are based on the recorded rig heave as well as the actual drilling fluid, well design and drill pipe data. Results show that there is a good correlation between simulated and actual measured downhole pressure. The surge & swab simulation software is then used to simulate the same drilling pipe connections using three different techniques and combinations of techniques utilized for improved downhole pressure control: (1) Managed Pressure Drilling (MPD) (2) Managed Pressure Drilling combined with Continuous Circulation System (CCS) and (3) MPD combined with CCS and a downhole choke. Results show that rig heave-induced downhole pressure variations are reduced to a level which is considered acceptable for drilling a well with narrow pressure window for the last two cases, while utilization of backpressure MPD alone is not sufficient. The combination of MPD and CCS reduced surge & swab for two out of three connections. For the third and deepest connection, the surge & swab increased. The largest reduction in significant downhole pressure variations (43-68 % vs. conventional drilling for the three connections) occurs when MPD and CCS are combined with downhole choking. Future work will consist of further developing the surge & swab simulator so that it will be possible to utilize it in well planning and as real-time decision support during drilling operations. The simulator will also be developed to include possibility of simulating various well completion operations such as running casings and liners. A prototype of the downhole choke is currently being tested at the mud loop of the Ullrigg test rig facility in Stavanger, Norway, and the next development phase consists of designing and building a complete downhole tool for testing in a well.
Verification of Downhole Choke Technology in a Simulator Using Data from a North Sea Well
The most important contributer to Improved Oil Recovery (IOR) on mature fields is drilling of infill wells. Managed Pressure Drilling (MPD) and Continuous Circulation System (CCS) techniques can be used for improved control of bottomhole pressure when drilling wells in depleted fields with narrow pressure windows, but rig heave is a challenge when drilling from floating drilling units. Rig heave, caused by sea waves, induces pressure oscillations downhole that may exceed the operational pressure window. These oscillations are called "surge & swab" and occur both during tripping in and out of hole as well as during drill pipe connections, when the topside heave compensation system used during drilling is disabled because the drill pipe is put in slips. Downhole choking was introduced as a method to reduce downhole pressure oscillations induced by the rig heave and the concept was tested in laboratory scale and using computer simulations (Kvernland et al., 2018). The simulations were perfomed using a purpose-developed software which utilizes such input variables as wave height, pump flow, drill pipe movements, rig characteristic (RAO), drilling fluid properties as well as well design, drill pipe and Bottom Hole Assembly (BHA) data to simulate downhole pressure, induced by rig heave. The simulator is designed to model dynamic interactions between the drilling fluid and the drill string in a rigorous manner, which gives it ability to accurately predict fast downhole changes, such as ones induced by ocean waves. This paper gives an overview of the surge & swab simulator, describing its capabilities and limitations. Data from drilling of a North Sea well is then used to validate the simulations made using the software. The well, used as example in this paper, was drilled conventionally from a floating rig. The downhole pressure variations recorded during three different drill pipe connections are compared with simulated downhole pressure. The simulations are based on the recorded rig heave as well as the actual drilling fluid, well design and drill pipe data. Results show that there is a good correlation between simulated and actual measured downhole pressure. The surge & swab simulation software is then used to simulate the same drilling pipe connections using three different techniques and combinations of techniques utilized for improved downhole pressure control: (1) Managed Pressure Drilling (MPD) (2) Managed Pressure Drilling combined with Continuous Circulation System (CCS) and (3) MPD combined with CCS and a downhole choke. Results show that rig heave-induced downhole pressure variations are reduced to a level which is considered acceptable for drilling a well with narrow pressure window for the last two cases, while utilization of backpressure MPD alone is not sufficient. The combination of MPD and CCS reduced surge & swab for two out of three connections. For the third and deepest connection, the surge & swab increased. The largest reduction in significant downhole pressure variations (43-68 % vs. conventional drilling for the three connections) occurs when MPD and CCS are combined with downhole choking. Future work will consist of further developing the surge & swab simulator so that it will be possible to utilize it in well planning and as real-time decision support during drilling operations. The simulator will also be developed to include possibility of simulating various well completion operations such as running casings and liners. A prototype of the downhole choke is currently being tested at the mud loop of the Ullrigg test rig facility in Stavanger, Norway, and the next development phase consists of designing and building a complete downhole tool for testing in a well.
A Rotational Continuous-Circulation Tool RCCT for Decreasing Non-Productive Time NPT and Mitigating Drilling Operational Risk
This work presents how a Rotational Continuous-Circulation Tool (RCCT) can decrease non-productive time and mitigate risks in the oil and gas drilling operations. The proposed tool provides almost continuous rotation of the drill-string and continuous circulation of drilling mud during the making/breaking of drill-pipe connections. Continuous rotation minimizes the stationary time during the connection. Thus, the risk of static contact between the wall of the formation and drill string (which can cause a differentially stuck drill-pipe) is reduced. This is one aspect by which non-productive time (NPT) is reduced, and the potential of encountering a differentially stuck pipe incident is mitigated. Continuous circulation enhances the hole cleaning efficiency. Rather than gravitating or being suspended, drilling cuttings continue to be removed to surface during connections with continuous circulation. As a result, the risk of having a mechanical stuck pipe incident (e.g., Pack-off) is prevented. In addition, maintaining continuous circulation eliminates down-hole pressure fluctuations. This reduces the risk of hole stability issues, and also enables navigation through zones with tight drilling pressure window. The proposed tool has been trial-tested twice to demonstrate its compatibility with the current drilling rigs/practices. Further trial tests are planned to demonstrate the added value of the tool.
Towards Achieving Indonesia's Oil Production Target of 1 MMBOPD by 2030: An Outlook from IATMI Norway
Indonesia has become a net-oil importer since 2004 as the growing internal demand exceeds Indonesia's oil production. As many fields go into mature phase and combined with other challenges, the national oil production in the last decade has been decreasing from 945 MBOPD to 745 MBOPD with a decline rate of 3-5% per year. Thus, the contribution of the oil and gas sector to the state revenues has also shown a downward trend from 21% in 2010 to only 9.2% in 2019. However,oil production is still strategically importantfor the national economy. It is important for economic value creation, power generation, transportation, and industries as most of the archipelago's infrastructures are still based on fossil energy. If no effort is made to increase production, the country will be fullydependent on crude oil imports, which poses a threat to national energy security. It is thereforeinthe nation's great interest to enhance oil production, minimizing the deficit gapbetween export and import. Several key strategies may be considered to achieve this ambitious target. These strategies can be categorized into the following: 1) People and high performing organization; 2) Exploration, as critical factor for future production; 3) Improved oil recovery (including enhancedoil recovery) technologies, to grow production from the maturing fields; 4) Fast track and simplified project to develop small field discoveries; 5) Strong collaboration between government, industry, academia, and professional associations; and 6)Cost conscious culture. The derivatives of the above-mentioned strategies are among others: standardized resource data management, open source & digitalized geoscience data library, reimbursement system for exploration costs, near field/infrastructure exploration,new play concept, cluster license collaboration, infill wells campaign, multilateral wells, waterflooding, gas injection, stimulation and hydraulic fracturing campaign, well interventions, EOR screening, perfect-well optimization, standardize subsea and/or topside production system, digitalization, and attractive fiscal and regulation that encourages not only the ‘big operator’ to participate in the petroleum sector. The foundation of these strategies should be the legal certainty and effective & proactive bureaucracy. Above all, it is also important to emphasize the common ground of havingearly HSE involvement as part of the solution. In this paper, the authors would like to contribute in sharing the knowledge, technology and perspectives to all petroleum industry professionals in Indonesia based on the authors exposure in the Norwegian petroleum activities. The paper will also review the strategies, short term and long-term opportunities that may inspire Indonesian petroleum authorities and industry in transforming the ambition into action to achieve the national production target of 1 MMBOPD and 12 BCFD gas by 2030.
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