Due to the ever-increasing demand for oil and gas, it is becoming more evident that getting the most out of the reservoir is crucial. For years, wells were drilled vertical or deviated, but horizontal and extended-reach trajectories are gaining more prominence. While the objective is to gain more access to the reserves, often the past methods of completions simply were not viable. In deviated wellbores, cased and cemented liner applications are difficult to obtain a good cement bond with the formation, and the inherent near-wellbore damage associated with cementing can lead to costly workover and stimulation treatments. Thus, open-hole completions are becoming more acceptable as the primary completion of choice. This paper will discuss the benefits of gaining as much contact with the reservoir as possible to create maximum drainage. It also will cover completion solutions (turnkey) that have been deployed around the world to better optimize recovery. Case histories will be provided that include multi-stage fracturing with swellable packers, inflow control devices with mechanical-set packers, geothermal hook-ups with openhole anchor, and multilateral completions with sand control and zonal isolation. Introduction In today's oilfield it is important to gain the most contact with the reservoir to ensure the maximum drainage. Cutting-edge measurement-while-drilling (MWD) systems allow operators to accurately place the well within feet of the planned location. Often the well geometry will take a more horizontal profile in the producing interval because the payzones are tighter and shallower than wells of the past. In addition, one well can now be the conduit for many producing reservoirs with the use of multilateral completions. As the wells are becoming more complex and inherently more costly, it is important to simultaneously minimize risk and maximize recovery. The solution to all of these challenges is to complete an openhole production zone to eliminate any operational risk associated with cementing and perforation. No two wellbores are the same and with the growing advances in technology, openhole completions systems can be customized to meet operators' specific needs or demands. Completions may involve multi-stage fracturing using reactive element packers, inflow control with mechanical-set packers, multilateral completions with zonal isolation, and geothermal completions with openhole anchoring. Multi-Stage Fracturing With Reactive Element Packers One of the most versatile tools for providing zonal isolation is the reactive element packer (REP) which uses wellbore fluid exposure to activate and seal-off desired zones. The reactive element (sometimes referred to as swellable packers) is an easy alternative to other packers because they require no intervention to set. This further simplifies the completion phase and therefore reduces additional risk from pumping and running an inner string. In recent years this technology has been widely adopted for use in openhole multi-stage frac applications. When used in conjunction with ball-activated sliding sleeves (as seen in Figure 1), an entire horizontal section (with up to 12 stages) can be pumped continuously without the need to run bridge plugs.

Drilling of horizontal wells continues to increase worldwide. A significant number of these wells are completed with either screen or slotted pipe across the production intervals. Many of these completions require some form of annular isolation to separate different geological zones and to isolate the upper wellbore. As a result, open hole completions are becoming more sophisticated, requiring a systems approach during the installation phase of the operation. Operators are also requiring that these completions be installed with the fewest drill pipe trips as possible to save time and reduce costs. The new integrated system described in this paper allows the production liner to be run into the wellbore and a liner top hanger system set, multiple external casing packers (ECPs) selectively cement inflated at target locations to provide zonal isolation and then the radius section of the production liner cemented to provide isolation between the liner and upper casing string. Using a newly designed hydraulically-operated cementing valve positioned in the liner above the uppermost ECP, the build section of the liner can be cemented after all the ECPs have been inflated. Using a workstring inside the liner in conjunction with a selective ECP inflation tool, cement can be displaced down the workstring, through the cementing valve, and out into the annulus. This new open hole completion method has been demonstrated to significantly reduce rig time during the installation phase, and provide the annular zonal isolation required by operators. The system also leaves the production liner free of cement, making subsequent cleanout runs unnecessary. P. 473

Tight gas and unconventional hydrocarbon wells bring forward HPHT well construction requirements. Typically, these wells require multistage high pressure stimulation, and, in most cases desired to be completed with openhole stage frac tools. These stage frac tools are exposed to repeated high pressure and temperature cycles during various stimulation and subsequent production activities. The increasing need to exploit such tight reservoirs pushes the endurance limits of conventional designs and elastomeric technologies required to deliver completion tools. This paper encapsulates invaluable information covering application, design and development of a complete HPHT multistage fracturing completion system with ball activated frac sleeves and packers. This system not only delivers a unique completion solution for HPHT stimulation and production, but, also incorporates distinct features from the pilot design to overcome common operational challenges in deploying this type of completion in difficult wells. In order to ensure the completion tools can handle this extreme well environment, the tools were tested at expected bottom hole conditions with numerous repetitive cycle tests beyond minimum acceptable API norms. During testing, various tool components and elastomers had to be redesigned or changed to pass the minimum qualification criteria; while maintaining compatibility to the well environment. During development and testing, the team had to employ Additive Manufacturing technologies for critical components to enable high expansion and to eliminate any extrusion gap of the openhole packer’s packing element. Further, in order to withstand the frequent temperature swings during operations, a more resilient elastomer was selected for the packer over traditional hydrogenated nitrile, FKM or FEPM compounds. Together, these provide increased functionality, by enabling handling of repeated loads and pressure cycles and pipe movement. This along with the other components of the multistage frac completion system and full 15,000 psi liner hanger and liner top packer provide a one of a kind robust HPHT stimulation system designed to enable well integrity at all times. The detailed design, functionality and testing performed eliminate the need for deployment of openhole anchors that are typically used to prevent movement of the packer due to pressure and temperature induced tubing movement. In addition, the system incorporates rotational and high circulation rate features to overcome common operational challenges for deployment in difficult wells. This unique multistage fracturing system brings the industry’s first openhole completion packer that utilizes additive manufacturing to go outside the boundaries of conventional tool manufacturi ng capabilities for HPHT stimulation application. Further, this system integrates the lower stage completion to deployment tools and upper completion providing a complete HPHT Stage Frac system from well head to toe. This reduces need for systems integrity testing or compatibility between tools during later planning and execution phase which is paramount for HPHT well construction.

This paper is a continuation of a previous work, SPE191734 (Deng, 2018) which focused on integrating additive manufacturing into completions technology to develop a packer of ultra-high expansion with a 10,000 psi pressure rating at 300°F. This paper presents the work that further extends the packer's capabilities to withstand pressures of 15,000 psi and temperatures up to 350°F while maintaining high expansion, tested to ISO 14310 V3 pressure acceptance criteria. Three factors primarily contributed to its successful qualification. First, new backup technology eliminated traditional design limitations imposed by conventional manufacturing and enabled us to design and print a backup system with ultra-expansion capacity and superior conformability. Second, an internally developed polymer that exhibits great elongation and extrusion resistance played a key role in holding the 15,000 psi pressure reversals at 350F in the ultra-expansion states. Finally, a state-of-the-art design process seamlessly integrated design, material characterization, design optimization, and test validation, enabling rapid failure diagnosis and design iterations to ensure rigorous customer requirements were satisfied. This integrated process reduces development costs and shortens time to market. An ultra-high expansion openhole HPHT packer was developed as a result of advances in Additive Manufacturing technology, polymeric materials, and a holistic design process. Physical test validation demonstrated: 15,000 psi pressure reversal and 15 minute hold at 350°F. Displacement of 0.5 in and 15,000 pressure reversal at 350°F. Elastomer element system remained in good visual condition in post-test inspection. This is the industry's first commercial completion packer with an Additive Manufactured element containment system. It is also the industry's first ultra-expansion packer to demonstrate HPHT capability.

Completion systems are reviewed for gas migration prevention composed of an annular casing packer with remote-set technology activated by either a surface mounted acoustic wave generator or a downhole casing wiper plug (CWP) with a magnetic array. Proven and reliable zero-extrusion gap element technology provides a gastight annular seal while reliability is enhanced by eliminating all communication ports and potential leak paths between the packer's ID and casing annulus. Design and qualification of these systems will be discussed along with successful field installations in 18⅝-in. x 24-in. casing strings in Sakhalin Island offshore wells.