A Breakthrough in Completion Technology—Development of Interventionless Hydrostatic-Set Isolation Packer for High-Pressure, Ultradeep Well

Abstract

An ultradeep well, as commonly drilled in the Gulf of Mexico, can run up to 35,000 ft of total depth. The pressure at such depths is extremely high, at approximately 22,500 psi. These wells require highly specialized rigs with expensive day rates; therefore, a significant part of the cost to drill and complete a well is the rig time. As such, minimizing the rig time results in significant cost savings. Often, these wells have a high deviation angle and "S" curve, placing the completion packers at the limits of wireline access. Therefore, completion planning is critical for a successful well completion execution and to reduce the rig time and operational risks. One way to eliminate multiple trips is to set the packer using interventionless methods. Many commercial products are available with designs using hydrostatic setting by means of atmospheric chamber(s), pressure pulse telemetry, and hydro-mechanical-chemical devices. However, these are not designed for the pressure demands of ultradeep wells. After careful consideration of the available products, a new high-performance, modular, removable, interventionless high-pressure-rated production packer that conforms with API SPEC 11D1 (2009) V0 validation grade was developed. Under a tight development schedule, the new product was developed to meet the needs of ultradeep well completions. The packer comprises slips for anchoring and elastomeric elements to provide a sealing capability for zonal isolation. A packer setting module was developed to be attached to the bottom of the packer and set the packer by enabling a fixed volume of high-pressure control fluid to flow from the packer setting chamber to the atmospheric chamber through an intricate flow conduit. An analytical calculation was performed to estimate the resistance coefficient for each feature of the flow conduit, which helped to calculate the macro-level flow characteristics (flow rate, overall packer setting time, and setting piston speed) and the micro-level flow characteristics (Reynolds number, differential pressure, kinetic head, and head losses at steady-state conditions) as well as to optimize the setting mechanism design. The same characteristics for transient flow were evaluated using computational fluid dynamics (CFD) analysis. An experimental proof-of-concept test was conducted on a small-scale version of the flow conduit and, to understand and validate the analytical flow behavior prediction and further optimize the flow conduit, an in-situ high-speed data-acquisition monitoring system was designed to record transient behavior at a high rate of 20,000 samples per second. The measured characteristics from the experimental test matched well with the analytical calculations and CFD analysis. Component-level testing was conducted on the packer element to verify element integrity at 15,000- and 20,000-psi isolation differential pressures. The component-level test was successful, enabling further rigorous testing per API SPEC 11D1 (2009) V0 validation grade, and the packer was successfully set at hydrostatic pressures of 5,000 and 27,500 psi and was validated for the full operating envelope in the unplugged condition, with an isolation differential pressure of 15,000 psi and an axial load of 600,000 lbf in a temperature range from 100 to 300°F. As a result, a breakthrough in technology was achieved by developing a high-pressure hydrostatic packer providing interventionless zonal isolation for an ultradeep well.