Challenges Associated with Drilling a Deepwater, Subsalt Exploration Well in the Gulf of Mexico: Hadrian Prospect

Moyer, M. C.; Lewis, Scott Bracken; Cotton, Michael Taylor; Peroyea, Miles

doi:10.2118/154928-ms

Cited by 6 publications

(1 citation statement)

References 4 publications

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“…Operators must demonstrate the ability to control the blowout under a WCD scenario to successfully apply for a drilling permit. Consequently, for deepwater and ultra-deepwater wells, the traditional wellbore casing design must be significantly altered to meet the new WCD criteria (Bowman 2010;Moyer et al 2012).…”

Section: Introductionmentioning

confidence: 99%

Blowout Well-Flow Simulation for Deepwater Drilling using High-Pressure/High-Temperature (HP/HT) Black-Oil Viscosity Model

Liu

Samuel

Gonzales

et al. 2015

Day 3 Thu, March 19, 2015

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One of the major risks associated with drilling an oil well is a blowout, or an uncontrolled release of hydrocarbons, which can lead to significant financial loss, environmental damage, personnel injuries or even casualties, and shaken shareholder confidence. Numerical simulation can offer some insight into well-flow parameters and wellbore integrity during a blowout event. Therefore, it is a powerful tool in casing design, blowout-preventer (BOP) stack design, drilling-process design, and well-kill design.In this paper, a field case was investigated using a commercial thermal and flow simulator. The effects of oil flow rate on wellbore temperature and pressure profiles were studied. Load analyses show that a blowout to atmosphere scenario is more detrimental to well integrity than a blowout to seafloor. In both scenarios, the maximum collapse load of the innermost casing increases with a decreasing blowout oil rate. This implies that if reservoir pressures are the same, deepwater wells with lower productivity indices will be more problematic in terms of well integrity.Simulation results also show that the viscous friction heat loss becomes significant at very high oil flow rates. During a deepwater-well worst case discharge (WCD) blowout, it is so significant that the wellbore temperature increases toward the surface along the smallest flow passage. The situation is even worse if the blowout fluids are discharged to the atmosphere. The physical root cause is explained in terms of fluid heat balance.A high-pressure/high-temperature (HP/HT) black-oil viscosity model was developed through modification of the Bergman-Sutton model. The HP/HT viscosity data of different crude oils with various API gravities were used to determine the model constant through regression. The effects of this HP/HT viscosity model are quantified in detail using the case-study data. The new viscosity model yields much higher accuracy in the HP/HT regime compared to other traditional, widely used models. Consequently, it facilitates higher certainty modeling and simulation of well discharge scenarios to satisfy current casing-design regulations in well exploration and development, from deepwater to ultra-deepwater conditions.

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Section: Introductionmentioning

confidence: 99%

Blowout Well-Flow Simulation for Deepwater Drilling using High-Pressure/High-Temperature (HP/HT) Black-Oil Viscosity Model

Liu

Samuel

Gonzales

et al. 2015

Day 3 Thu, March 19, 2015

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Ultra-Deepwater Blowout Well Control Analysis under Worst Case Blowout Scenario

Yuan

Hashemian

Morrell

2014

Day 1 Wed, September 10, 2014

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For offshore wells, the regulatory agency requires the submission of a worst discharge analysis and relief well planning report. The ability to control the blow out under worst case blowout scenario shall be documented and is a requirement for the operators to successfully apply for a permit to drill in the US offshore fields. As the water depths of offshore drilling operations are getting deeper and deeper, due to the increased frictional pressure losses in kill lines and formation fracture strength, bringing the blow out well under control with worst case discharge becomes more challenging. Operational parameters need to be carefully controlled to avoid exceeding the operational limitations such as breaking the formation or exceeding available pump capacity. In this study, dynamic simulations of multiphase flow are carried out to evaluate the operational parameters during the kill process. The simulations account for transient changes including frictional pressure losses, U-tube effect and fluid density variations. By optimizing the operational sequence with regards to, kill mud density, pump flow rate, pump down staging, relief well drillstring and trajectory, blowout can be controlled without exceeding the operational window. The paper shows the required volumes of the kill mud, required pump capacity, optimal flow rate arrangement, and minimum time required to get full kill mud return to the sea floor during the well kill operation. Through the aid of advanced transient software models, assessment of the required capacity to kill a blowout enables development of realistic contingency plans to ensure that well control can be re-established in case of an ultra-deep water worst blowout scenario.

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Assessment of Fracture Containment and Broaching Resulting From Worst-Case-Discharge Events

Zaki

Dirkzwager

Hilarides

et al. 2015

SPE Drilling &Amp; Completion

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Summary “Worst-case discharge” is a relatively new term given to a hypothetical event that is deemed to be of low probability but of high impact. The consequences of such a discharge are substantial on drilling and completion operations for a specific well. It may also have significant implications on a fieldwide and, perhaps, companywide basis. This paper assesses, hypothetically, the circumstances that lead to such an event and the occurrence's subsequent impact on the subsurface. A hypothetical worst-case-discharge incident could be started by a kick (influx of high-pressure fluid into the wellbore during drilling). In such a hypothetical event, casing collapse could occur under the differential load (pressure within the casing is reduced significantly whereas pressure outside the casing remains high). After capping and controlling the well occur, pressure buildup occurs. Fluid could escape through the collapsed casing and migrate to surface, by means of conduits such as open annuli, unconsolidated sedimentary sequences, fractures, and salt sutures. For example, an open annulus can displace fluid to shallower horizons. Alternatively, the fluid pressure can propagate a fracture that could then broach to the surface or mudline. The paper reviews such a hypothetical event and discusses design changes targeted at mitigating and/or remediating potential negative impacts. The concept presented revolves around the positioning of casing shoes to force fracture propagation into particular horizons, thus minimizing and remediating the effects of the discharge event.

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Challenges Associated with Drilling a Deepwater, Subsalt Exploration Well in the Gulf of Mexico: Hadrian Prospect

Cited by 6 publications

References 4 publications

Blowout Well-Flow Simulation for Deepwater Drilling using High-Pressure/High-Temperature (HP/HT) Black-Oil Viscosity Model

Blowout Well-Flow Simulation for Deepwater Drilling using High-Pressure/High-Temperature (HP/HT) Black-Oil Viscosity Model

Ultra-Deepwater Blowout Well Control Analysis under Worst Case Blowout Scenario

Assessment of Fracture Containment and Broaching Resulting From Worst-Case-Discharge Events

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