The Shearwater field is a deep, high-pressure, high-temperature (HPHT) reservoir located in the UK Central Graben of the North Sea. The current drilling campaign represents the first round of well re-entries into the field following a campaign of slot recoveries to facilitate sidetrack development opportunities.A high level of reservoir depletion (Ͼ 8000 psi) has resulted in significant changes to the drilling envelope that has added complexity to the drilling practices required to successfully exploit the remaining reserves.Managed Pressure Drilling (MPD) Technology was pursued as an enabling technology to navigate within some very narrow margins in the first well of the redevelopment campaign. MPD was implemented in conjunction with drill-in liner and wellbore strengthening technologies to successfully deliver this first well and prove the techniques required to prolong field life.To promote successful implementation of MPD in the target zone, the technology was employed in the previous hole section to gain experience with the equipment and procedures where pressure control was less critical.MPD was used to control bottom hole pressure to manage background gas and facilitate changes to equivalent mud weight. It was further used to minimise the effects of loss/gain mechanisms and enable drilling through a tight margin between pore and fracture pressure while reducing the risk of borehole instability and losses. The technology was also used to determine appropriate mud weights for tripping and provide trip margin to avoid swabbing while tripping. In addition, MPD was used to facilitate cementing in tight margins. This paper will highlight the multiple uses of MPD throughout the start-up of this current drilling campaign and key learnings enabling successful implementation of a new technology on the rig. Shearwater OverviewShearwater is a HPHT gas condensate field discovered in 1988 and located in the UK Central Graben of the North Sea. Primary production is from the Fulmar -a sandstone reservoir with virgin pressure of 15,400 psi and temperatures Ͼ 360°F. MPD Objectives by Hole Section ¼؆ Hole Section to Top Cromer KnollMPD was not planned as a requirement for this hole section. The primary objective for MPD in the 12 ¼Љ hole was to gain experience and shakedown the equipment, rig-up configuration and procedures on a rig using MPD for the first time.Although not a primary objective, MPD could also provide enhanced kick detection capability in the event of higher than expected pressures (especially through the Hod Mass Flows -discrete layers of hard, low porosity chalk interbedded with marls within the Hod formation and commonly associated with high background gas levels while drilling), loss detection capability in the event of lower than expected pressures and the ability to test the drilling window through dynamic pore pressure and FIT/LOT tests.MPD could also be used to allow a lower mud weight to facilitate identification of the pressure ramp in the Tor and promote faster rates of penetration through the chal...

One of the main constraints facing many offshore platforms is the shortage of accommodation. The balance between continuing field development and maintaining existing production and platform integrity inevitably requires a compromise in the crew allocation for well engineering activities. This paper will discuss the challenge faced on Shell's Gannet Alpha platform in conducting a coiled tubing managed pressure drilling (CTMPD) operation with a 20% reduction in crew numbers over the previous CTMPD operation. The key enabler of this reduction was the use of a supplier's established onshore control centre located in Norway for remote support. A two-way real time data connection from the platform was established that allowed two key roles to be removed from the platform - drilling data acquisition and quality control, and control of a dynamic annular pressure control system. This implementation of remote support was unique as the main drilling supplier not only used this facility to reduce his rig-site presence but also facilitated other third party suppliers to remotely operate their equipment by providing space and IT infrastructure within the facility. As well as the principle benefit of reducing personnel on board required to run the CTMPD, additional benefits were realised through the dissemination of real-time data throughout the operator and supplier organisations. By utilising the WITSML data protocol, the operators reservoir model and well-planning programs were populated in real-time enabling subject experts to participate in the decision making process. Additionally, onshore technical support and engineering personnel were able to utilise the two way connection to access the offshore systems in real-time in order to troubleshoot problems, perform software upgrades and carry out diagnostics on surface hardware and downhole tools as required. This paper will describe the upfront preparation both in terms of the IT infrastructure and the personnel multi-skilling. It will then describe the ways in which the data was transmitted and used during the operation, and the contingency procedures that were developed in the event of loss of communication. Finally, the future of real time operations will be discussed and how the learnings from this operation can be used in the ongoing development of this technology. Introduction Background The Gannet 'A' platform is located in the central North Sea, approximately 120 miles East of Aberdeen. As well as the Gannet 'A' field, there are a further 6 subsea fields tied back to the platform. A requirement for infill drilling was identified in order to continue the development of the field. Drilling Methodology The original Gannet A wells were drilled with the assistance of a tender vessel which primarily provided pumping, fluids handling, solids control and accommodation services. An infill drilling feasability study concluded that re-instatement of the existing platform drilling equipment was not viable and that coiled tubing drilling was the most economic option for accessing the stranded reserves.

With water production continuing to increase from mature reservoirs and the need to enhance hydrocarbon recovery from these reservoirs economically using existing wellbores, the requirement for innovative thru-tubing zonal isolation solutions has never been greater. Due to the complexity of the completion design and reservoir in mature fields, the benefits of high-expansion plugging devices and coiled tubing conveyance for chemical placement have become increasingly important. Thru-tubing inflatable technology has, for some time now, been providing high-expansion devices to pass through the existing completion and isolate in the liner or casing below. However, as reservoirs deplete and remedial work such as re-perforation is performed, the conditions in which these tools are required to perform are becoming ever more challenging. This paper will focus on two coiled tubing water shutoff interventions using thru-tubing inflatable technology in conjunction with cement or chemical placement. In these interventions, the wellbore conditions were considered particularly challenging - sub-hydrostatic bottomhole pressure, multiple perforated intervals and an existing zonal isolation device in the form of a straddle. These case histories will be examined in detail, with emphasis on the pre-job planning, equipment selection, operational procedures, lessons learnt and post job results. Introduction In order to maximize the chances of success of a thru-tubing inflatable water shutoff intervention, it is imperative to properly plan the intervention. The following key aspects of the planning phase have been identified and should always be given full consideration:Gathering of complete and accurate wellbore informationFull understanding of equipment limitations to ensure operating envelopes are not exceededPreparation of the wellbore prior to thru-tubing inflatable intervention In order to facilitate the pre-job planning process, a number of initiatives have been developed and are used to ensure that the aforementioned key aspects are fully addressed. These initiatives have been discussed more fully in SPE 54476 - "Through Tubing Inflatables: Isolation Planning and Guidelines for Coiled-Tubing Applications" and some are listed below:Client intervention planning guidelinesStructured interface document for recording of well bore informationUse of memory pressure/temperature gauges in drift runsEngineering analysis aided by software and performance envelopeIncreased global communication via webcasting techniqueProblem solving/risk matrix for mitigation of risks to success of intervention This paper will provide a detailed analysis of two particularly challenging thru-tubing inflatable water shutoff isolations, and will demonstrate how several of the aforementioned initiatives were used to maximize the chances of success of the interventions.