Trends in offshore exploration continually push the definition of high pressure and high temperature in regards to oil and gas well completions. Recent discoveries in the Gulf of Mexico (GOM) are opening up vast reserves of natural gas and these discoveries are again challenging that definition. To meet the need of high-pressure, high-temperature (HPHT) applications in general and for an operator in one such HPHT field, an ultra high-pressure and high-temperature rated wellhead plug and downhole plugging system has been developed to provide wellbore integrity in extreme conditions. This paper addresses the challenges associated with development of slickline-retrievable equipment rated to 25,000 psi at temperature extremes from 32°F to 450°F and the approaches used to overcome those challenges. A review of design considerations, sealing technology, design verification, and validation testing that exceeds industry standards, is also provided.

Following successful field applications of solid-liner drill-in systems, efforts now focus on drill-in sand screen liners. This paper will discuss enabling technologies to meet the peculiar challenges of drill-in sand screen liners. The screen liner must contain pressure when drilling to allow circulation through the bit and wellbore inflow during production. The screen's filtration media must also be protected from possible plugging during drilling. Rotating the screen liner to allow circulation may damage screens, so a drilling motor at the bottom of the liner drives the bit. Conveying fluid to the motor using a conventional inner circulating string may add sufficient weight to significantly limit horizontal and highly deviated well angles. This paper addresses a technology that temporarily blocks flow through the screens during drilling to allow a pressure-tight circulation path through the liner to the motor without the need for an inner circulation string. Once drilling is complete and the liner is in place, the screen joints are simultaneously opened using hydraulic pressure applied within the liner, and the well is ready to be put on production. Temporarily closing off of the screen joints also has additional applications, such as simultaneously setting hydraulically-set open-hole packers without an inner circulating string. The paper also discusses a time- and temperature-sensitive protective film applied to the screens during fabrication to prevent fluid egress into the filtration media until the film dissolves. Sufficient time for dissolution is designed into the film to allow the liner to be drilled into place while protecting the screen's filtration media from possible plugging during drilling. Testing and applications of these technologies are discussed, along with economic advantages resulting from savings in rig time and improved success rates for properly placing screen liners. Operational aspects associated with this new system are outlined with regard to system components and job design. Introduction Drilling solid liners in place, either as a reaming application where a pre-drilled hole is present, or drilling the borehole without a pre-drill, has been successfully utilized in recent years. Drill-in solid liners have proven valuable in difficult drilling conditions, such as drilling in formations with weak matrix strengths, loss circulation zones and tight pore pressure/fracture gradient windows 1. The predominant problem when running screen liners, however, is borehole collapse in sensitive shale sections during the time between drilling the hole and running the screens. Failure to run the screen liner to TD may have serious consequences, especially when zone isolation packers are spaced out in the liner to correspond to geologic features in the wellbore. When this problem is encountered, the screen liner can be rotated and reciprocated in an attempt to pass through the collapse section, however, risks of mechanical damage and plugging of the screen filtration media results. Normal screen running procedures caution against rotation of the liner in the openhole for this very reason. To address this problem, a simplified screen drill-in system is envisioned which can open collapsed sections of the borehole as required when running into a pre-drilled hole. Unlike liner-casing drill-in systems, which utilize rotary drilling technique, the screen drill-in system is based on using a mud motor and bit assembly in the liner assembly. Limitations in the ability to rotate the screen, coupled with reduced torsional capability of the screen basepipe due to inflow holes, render a rotary drill-in method with screen liners impractical. Current technologies developed for general sand control and liner drilling can be utilized in developing a screen drill-in system 2. Since torque will not be applied through the drill pipe and screen liner, except for the generated reactive torque from the mud motor, most of the system components are already available, such as liner hangers, running tools and liner-top packers. There are, however, deficiencies in the current screen system which are not compatible with a screen drill-in application. The obvious problem when drilling with screens is that they are not designed, by definition, to contain pressure.

Following successful field applications of solid-liner drill-in systems, efforts now focus on drill-in sand screen liners. This paper will discuss enabling technologies to meet the unique challenges of drill-in sand screen liners. Rotating the screen liner to drive the bit may damage screens, so a drilling motor at the bottom of the liner must be utilized. Also, conveying fluid to drive the motor and remove debris is required. Using a conventional inner circulating string inside the screen liner may be prohibitive due to the addition of sufficient weight which may significantly limit horizontal and highly deviated well angles and length. The screen liners therefore must be able to contain pressure when drilling to allow circulation through the bit, and subsequent wellbore inflow during production. Additionally, the screen's filtration media must also be protected from possible plugging with solids during drilling. This paper addresses a new technology that temporarily blocks flow through the screens during drilling/reaming to provide a pressure-tight circulation path through the liner to the motor, eliminating the need for an inner circulation string. Once drilling is completed and the liner is in place, the screen joints are simultaneously opened using hydraulic pressure applied within the liner, and the well is ready to be put on production. Temporarily closing off the screen joints also has application for simultaneously setting hydraulically set open-hole packers remotely without an inner circulating string. The paper also discusses a time- and temperature-sensitive protective film applied to the screens during fabrication to prevent fluid egress into the filtration media until the film dissolves. Sufficient time for dissolution is designed into the film to allow the liner to be drilled into place while protecting the screen's filtration media from possible plugging during drilling/reaming. Qualification testing of these technologies are discussed, along with additional applications for this technology where utilizing a temporarily closed screen system has advantages. Introduction Drilling solid liners in place, either as a reaming application where a pre-drilled hole is present, or drilling the borehole without a pre-drill, has been successfully utilized in recent years. Drill-in solid liners have proven valuable in difficult drilling conditions, such as drilling in formations with weak matrix strengths, loss circulation zones and tight pore pressure/fracture gradient windows1. The predominant problem when running screen liners, however, is borehole collapse in sensitive shale sections during the time between drilling the hole and running the screens. Failure to run the screen liner to TD may have serious consequences, especially when zone isolation packers are spaced out in the liner to correspond to geologic features in the wellbore. When this problem is encountered, the screen liner can be rotated and reciprocated in an attempt to pass through the collapse section, however, risks of mechanical damage and plugging of the screen filtration media results. Normal screen running procedures caution against rotation of the liner in the openhole for this very reason. To address this problem, a simplified screen drill-in system is envisioned which can open collapsed sections of the borehole as required when running into a pre-drilled hole. Unlike liner-casing drill-in systems, which utilize rotary drilling technique, the screen drill-in system will be based on using a mud motor and bit assembly in the liner assembly. Limitations in the ability to rotate the screen, coupled with reduced torsional capability of the screen basepipe due to inflow holes, render a rotary drill-in method with screen liners impractical. Current technologies developed for general sand control and liner drilling can be utilized in developing a screen drill-in system2. Since torque will not be applied through the drill pipe and screen liner, except for the generated reactive torque from the mud motor, most of the system components are already available, such as liner hangers, running tools and liner-top packers. There are, however, deficiencies in the current screen system which are not compatible with a screen drill-in application. The obvious problem when drilling with screens is that they are not designed, by definition, to contain pressure. Screens are filtration elements. Thus, the screen design must be altered to contain pressure during drilling to supply a flow path for fluid to power the motor, or an inner string must be utilized during run-in to isolate the screens.

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