Smart well completions include downhole gauges, sliding circulation valves, open/close safety valves, control lines, and fiber cables or a combination of these. One method for deploying this downhole equipment is achieved by affixing it to the outside of the casing and permanently cementing it in place; however, a challenge with external-casing equipment is helping to prevent damaging the installation if perforating is the chosen method to establish effective communication between the wellbore and formation. This challenge is further magnified when the well is drilled near-vertical and run on the outside of a large-diameter casing. This paper discusses the execution of an engineered design of service to perforate a 7-in. diameter production smart well completion using 4 5/8-in. tubing-conveyed perforating (TCP) gun assemblies. As part of the completion design, the TCP gun assemblies were hung below the bottomhole assembly (BHA). A fiber-optic (FO) package was run external to the casing, and the well had a deviation less than 5°, preventing the use of high-side logging tools. Various options, discussed later in this paper, were considered to locate the azimuthal orientation of the fiber cables, including a new-to-market technology tool. Ultimately, a method was devised to engineer an ultrasonic logging tool to be deployed in conjunction with a north-finding gyroscope tool to accurately determine the location of the external-casing equipment. TCP guns were then hung below the tubing string, which included a fixed-point orienting sub that could be used to confirm the direction of all the planned perforations. To achieve operational and economic objectives, the TCP assembly was dropped to the bottom of the well so that the well could be immediately placed on production without killing the well or retrieving the spent perforating guns. The well was successfully perforated without damage to the external-gauge equipment, showcasing that collaborating with the operator, and understanding their value drivers, led to an engineered solution that maximized the asset value of the well.
Optical fiber flatpacks, which are cable-reinforced plastic-encased fiber bundles used for local temperature and acoustic measurements, can be stressed when near a perforating gun. The fiber itself is floated in metal tubes with gel. Understanding the behavior under severe shock causes the use of potential mitigation schemes. In this work, the flatpack containing optic fibers is simulated for survivability on the casing of a perforating gun system. Using a shock hydrocode in two-dimensions (2D), a flatpack is simulated on the 5 1/2-in. casing of a 3 3/8-in. gun with a 21-g shaped charge. Effects of concrete encasement, clamps, and off-angle shots are considered. The view is in the plane of one shaped charge. Quantitative results include pressure temporal profiles, velocity profiles, and g acceleration at the fibers. Pressure at the flatpack peak is in the hundreds to thousands of psi, and accelerations peak in the hundreds to thousands of g. Unconfined flatpacks tend to launch from the casing, while confined flatpacks tend to oscillate at their location. Pressure contour models show the shaped charge breaking into multiple pressure pulses. The primary shocks are in front of and behind the charge. Secondary pulses occur off-axis near the base of the charge and from the jet bow shock near the top of the charge. Overall comparative simulation results indicate optimum flatpack location and configuration. Novel mitigation schemes are identified and simulated. A fiber-optic flatpack has been simulated in a zero- degree loaded gun for the first time; this information helped with understanding survivability against shaped charge shocks.
During perforating operations, identifying the orientation of fiber cable accurately is critical for maintaining the integrity of permanently installed fiber.Beyond completions,it alsoprovides insights into how the casings get twisted and how the mechanical stability of the casing is altered as the string is run in the hole. The drilling and completion system is as unique as the aspect ratio and length/diameter is very high. This puzzles the researchers in modeling forces, stresses, stretch, and twists. To aid the accurate prediction in the position of the casing, radial orientation of downhole fiber optic cables canbe used. The clear images obtained by mapping the equipmentoutside thecasing provides not only how the casings get twisted after running in but also provide improved risk mitigation for perforating operations.The orientation angle of the casing versus depthis then analyzed to get the finaltwist and pitch of the twist of the casing. Several wells datawere analyzed to get a comprehensive view of the casingtwist as the casings were run and versus the model prediction. The raw data obtained using the pulsed-eddy current time-domain decay at each station are used for the analysis. Each installed cable detection clamp (CDC) is placed above a casing centralizer located 2' above each joint of casing that had a clamp installed.This simplifies the process of locating the depth of each CDC. A casing collar locator easily identifies the casingjoints.Further, the data are used to find the casing rotation. Several wells showed normal casing rotation of 2–3 wraps along the lateral and onewell showed more than 12 wraps. Several reasons were considered and analyzed including the wellbore spiraling, borehole torsion,and additional mechanical forces applied duringrunning the casing. The coupling of the geometrical and mechanical twist and mechanical stability of the string are discussed in the paper withmathematical underpinnings. In thecase of abnormal prediction, additional mechanical forcesandgeometrical considerations were overlapped and comparedagainst the torque and drag model prediction.It has also beenfound that in some wells where the wellbore torsion washigh,it resulted in a complete twist of 360° atthe heel and in some cases negative trend.
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