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Gabaldon, Oscar (Blade Energy Partners, Ltd.) | Gonzalez Luis, Romar (Blade Energy Partners, Ltd.) | Brand, Patrick (Blade Energy Partners, Ltd.) | Saber, Sherif (Blade Energy Partners, Ltd.) | Kozlov, Anton (Blade Energy Partners, Ltd.) | Bacon, William (Blade Energy Partners, Ltd.)
In high pressure high temperature (HPHT) reservoirs and exploratory wells, especially in deep water, there is a higher degree of uncertainty, which can increase the operational costs due to non-productive time (NPT) and operational problems due to the unpredictable nature of these wells. For these challenging wells with narrow windows, Managed Pressure Drilling (MPD) techniques offer cost-effective tools to increase the odds for achieving well and cost objectives assurance. There are significant benefits from early implementation of MPD in the project life cycle. These benefits include from improving operational efficiency to risk mitigation and safety enhancement. However, there is an enormous potential that many operators have been missing. This is related to the incorporation of MPD as a driver in optimizing the well design, which could greatly increase the possibilities of reaching target depth, and potentially prepare to eliminate one or more casing strings. Current well design process hinges on the ability to manage uncertainties by company or regulatory requirements, such as kick tolerance and safety factors. This work addresses the value added from implementing MPD in early stages in the project life cycle through the analysis of case studies. The cost savings from the impact on the well design are also discussed. This work also presents a in depth discussion on the benefits, and enablers of this approach. Furthermore, it presents considerations by taking advantage of dynamic processes facilitated with MPD. Finally, new guiding criteria to aim to constitute a systematic and integrated approach to ensure well integrity and optimize well design while also considering the operational implications and integral cost benefits is proposed to the industry. This paper represents the initial phase of a compressive long-term project to integrate two main components of well design. These are MPD adaptive well design, and statistical analysis based on variations of load and/or strength.
Kaldirim, Omer (Texas A&M University) | Kaldirim, Ebubekir (Louisiana State University) | Geresti, Cameron (Texas A&M University) | Manikonda, Kaushik (Texas A&M University) | Schubert, Jerome J. (Texas A&M University) | Hasan, Abu Rashid (Texas A&M University)
Limited studies are available for modeling gas migration in risers. Outdated and small-scale models provide insufficient reliability, and a thorough mechanistic description of the problem is still not available. A significant part of the problem concerns understanding how pressure, temperature, liquid properties, and gas-liquid dynamics effect gas expansion during migration.
This paper provides information on Computational Fluid Dynamics (CFD) simulations performed on gas injections in three static and dynamic vertical fluid columns, with and without back pressure measuring 27-ft. and 330-ft. tall with 6, 12, 19.5 in. diameter. These CFD simulations analyzed the recorded gas expansion, change in pressure and temperature, and the volume fraction of the gas throughout the riser. In addition, these simulations also analyzed the change in flow rate, velocity, and the unloading effect at the inlet and outlet.
The 330-ft. pipe simulation demonstrated explosive unloading behavior with maximum discharge velocity and flow rate of over 2.8-ft./sec. and 6617.5-gpm., while the shorter pipes demonstrated relatively slower overflow. The case with a 330-ft. pipe also recorded a rapid change in temperature close to the top. Back pressure application at the surface minimized the effects of unloading and slowed down expansion.
Bermudez, Raul (TOTAL) | Ferro, Juan Jose (TOTAL) | Szakolczai, Cyril (TOTAL) | Birades, Christophe (TOTAL) | Conil, Luc (TOTAL) | Hernandez, Julian (Weatherford) | Brinkley, Ryan (Weatherford) | Arnone, Maurizio (Weatherford) | Carreño, Leonel (Weatherford) | Hollman, Landon (Blade) | Torres, Ivan (Halliburton)
The operation described in this paper is related an ultra-deep-water exploration well drilled in the Mexican waters of the Gulf of Mexico (GOM) and the first drilled by the operator in the area. From the onset of planning, the base case was to integrate a Managed Pressure Drilling (MPD) system into the drilling program to assist with pore pressure uncertainty, pressure ramp increase, and narrow Pore Pressure/Fracture Gradient (PP/FG) window operations including drilling, tripping, running casing and cementing, with the latter being a procedure that was not included in the initial stages of the project but discussed and implemented during the execution phase (
The well is located in a water depth of 3,276 m (10,748 ft). Given the exploratory nature of the well, there was an assumed pressure ramp that would demand an excessive number of casing strings with a conventional approach using an overbalanced Mud Weight (MW). During the drilling phase and taking advantage of the ability to adjust the bottom hole pressure instantaneously, dynamic pore pressure tests were performed to conclude that the pressure ramp was not as aggressive but lead to a narrow window that would not allow conventional cementing of the 13-3/8-in. casing.
Strong planning was required between the operator's engineering and operations teams, cementing services provider, MPD consultant, and MPD service provider team. The uncertainty about the actual size of the hole yielded an even more challenging Managed Pressure Cementing (MPC) engineering analysis (
The specific objective for the MPC application was to set 13-3/8-in. casing to isolate the critical formation and to safely continue drilling further stages of the well with an improved Leak-off Test (LOT) at the shoe.
This job represents the deepest water, and first from a drillship, for a managed pressure cementing job performed by both operator and MPD service provider. Additionally, a critical cementing operation was successfully performed using the Managed Pressure (MP) approach. The well construction objectives using MPD were also achieved while avoiding the use of a contingency liner which saved an additional USD3.5 MM from the planned AFE (
Gu, Qifan (The University of Texas at Austin) | Fallah, AmirHossein (The University of Texas at Austin) | Gul, Sercan (The University of Texas at Austin) | Ashok, Pradeepkumar (The University of Texas at Austin) | Chen, Dongmei (The University of Texas at Austin) | van Oort, Eric (The University of Texas at Austin) | Moore, Dennis (Marathon Oil Corporation)
Non-aqueous drilling fluids used in deepwater drilling operations are conducive to the dissolution of formation gas during wellbore influx events, increasing the risk of gas kicks going unnoticed. This can lead to hazardous riser gas unloading events if kicks are allowed to pass the subsea BOPs and come out of solution at the bubble point at shallow riser depth. One possible solution to handle and even prevent these events is to generate enough backpressure using Managed Pressure Drilling (MPD) with a Rotating Control Device (RCD) to keep the dissolved gas in solution. However, for large kicks, the required backpressure may exceed riser pressure limits.
A novel kick handling procedure using a dilution control strategy (DCS) is proposed here to handle gas influxes and subsequent gas unloading events. The idea behind this DCS is to inject mud into the riser through the boost line while simultaneously slowing down the circulation rate through the drillstring as the dissolved kick passes the open subsea BOPs. The kick will then get diluted and will be distributed across a larger annular space leading to a significantly decreased gas concentration that can be more easily handled by the MPD system with lower backpressure.
The feasibility of the DCS is investigated in this paper using a multi-phase flow model which is validated against experimental data for a gas kick in oil-based mud. Simulation results for a demonstration case show that a kick entering the well at 18,500 ft with 2,250 kg gas can be thoroughly eliminated with a 3:1 dilution ratio (which is the ratio of riser boost rate to drillstring circulation rate) with approximately 620 psi backpressure when using an MPD system. To improve the applicability of the proposed DCS procedure in field practice, a data-driven approach is implemented using simulated data points to provide a fast estimation of the optimum dilution ratio (DR) to control the kick in real-time.