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.
The objective of the paper is to present a case where a Managed Pressure Drilling (MPD) and an MPD Well Design process was used to design and drill a deepwater exploration well with an expected pressure ramp and narrow drilling margins while acquiring valuable subsurface data. The expected pressure ramp and narrow drilling margins combined with the uncertainty of subsurface data presented significant challenges to the well design team. Based on previous experience in the region, reaching well TD safely and efficiently using conventional drilling methods was predicted to be challenging. The MPD Well Design process enabled MPD techniques, including constant bottom hole pressure and dynamic influx management, to be integrated into well design process. MPD was also identified as a critical tool to collect dynamic pressure data and help reduce overpressure uncertainty. The drilling program, rig specific operations, and contingency procedures were developed accordingly. MPD was used to successfully drill through a pore pressure ramp and address a well control event in conjunction with conventional methods. MPD was also an enabler to optimize the location of the casing/liner shoes by identifying the pressure profile based on real-time pore pressure data. This feature was a key advantage to drilling deeper than planned and resulted in effectively saving one casing string. The proposed well design included five casing/liners, with potential for two contingencies. With the implementation of MPD, the actual well was drilled with four casings/liners to a deeper TD and met all evaluation objectives under budget. This paper presents a case for using MPD and the MPD Well Design process and its full capabilities to optimize all aspects of a well delivery process, including well design, safety, and subsurface data acquisition.
Technology improvements are continuing to expand the capability of coiled tubing directional drilling (CTDD) worldwide. Increased CTDD activity in advanced underbalanced re-entry applications that require precise wellbore (multilateral) placement and real-time monitoring of downhole parameters has led to the development of bottom-hole drilling assemblies (BHAs) with enhanced functionality. Saudi Aramco identified CTDD as an important technology for redeveloping its gas reserves and is dedicated to expanding the technical limit of CTDD application. Saudi Aramco successfully completed its first underbalanced re-entry coiled tubing drilling (UBCTD) pilot project and is now progressing to consolidate this technology in subsequent UBCTD operations. A great impetus has now been placed on further improving UBCTD project economics through improved operational efficiency and the introduction of new underbalanced coiled tubing drilling techniques and services. This paper provides an overview of the new Rib Steered Motor (RSM) technology and its potential benefits to UBCTD. It details recent worldwide deployments of the rib steering motor technology focusing on operations in the Kingdom of Saudi Arabia which provide the perfect testing ground when geosteering with RSM. Future advances using UBCTD geosteering technology rely on a close working relationship between the field operator and the service company. Successful application of UBCTD applys to a wide range of mature oil and gas fields for enhancing access to the producing reservoir to drive the economic extraction of additional reserves.
This paper presents a case where Managed Pressure Drilling (MPD) was used to drill a challenging exploration well through a pore pressure ramp and to address a well control event in conjunction with conventional methods when an influx was encountered The MPD system was used to drill using primary and secondary indicators, such as background gas, cuttings shape, and changes in ROP to determine if onset of the pore pressure ramp was imminent. The MPD system provided a means to measure the flow in versus the flow out of the well and chokes to add surface back-pressure (SBP) to adjust the bottomhole pressure. The MPD operators monitored the trends as drilling continued and reacted if any indications of a pore pressure ramp were experienced. The pressure ramp was encountered, and the flow out exceeded the flow in. The driller applied more surface back pressure to control the influx and reduce the influx size. The well could not be controlled within the allowable back pressure limitations as outlined by the MPD Operations Matrix, so the well was shut in on the Subsea Blow-Out Preventer (SSBOP). The well was controlled with conventional well control methods, using the Driller's Method. The mud weight was increased to the extent that it was not enough to hydrostatically kill the well, but sufficient to allow operations to resume within a new MPD Operational Matrix adding back pressure to keep BHP overbalanced to the formation. This application of MPD reduced the impact of the influx event and allowed the rig to safely continue drilling and meet the well objectives without losing the hole section.
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