Abstract
Abstract
One of the most cost-effective methods of completing an openhole well for oil and gas production is to gravel pack the openhole interval using sand screens and sand management devices to control the production of formation sand. In general, hydrocarbons can be produced from wells in one zone or wells spanning several production zones. As the wells get deeper, producing from multiple zones becomes a cost-effective option, especially in offshore environments. The most-common method to achieve gravel packing for multizone openhole completions is to use a conduit system—either a set of tubes or a concentric sleeve to bypass the isolation device and transport the proppant to the lower zones. Operationally, the tubes are designed to withstand screenout pressure. Screenout is a pressure spike that occurs at the end of gravel packing, indicating the zones has packed. The current systems are designed for low to medium screenout pressures of up to 6,000 psi. But for deepwater wells, the tubes need to be designed to withstand greater screenout pressures to provide a reliable openhole gravel-pack sand control solution for extended-length, multizone, and high-pressure, high-temperature wells. In addition, the leak path through the shunt tubes for fluid migration between producing and nonproducing intervals was a concern to achieve total zonal isolation.
This paper discusses a comprehensive design approach for the rapid development of a high-pressure conduit system for total zonal isolation following gravel-packing operations. The architecture goal was to make no changes to the packer seal and setting system to enable concurrent manufacturing of the packer. A comprehensive risk matrix using design failure mode and effects analysis (DFMEA) was established to capture risks and formulate a derisking strategy. The significant risks were evaluated using finite element analysis (FEA) techniques, and extensive modeling and simulation were performed on pressure and buckling failures. A comprehensive computational fluid dynamics (CFD) analysis was performed to simulate the erosion of the system during gravel packing. The system was modeled with reduced thickness, and pressure simulation was performed using FEA at a minimum material condition to verify the design. All failure modes were studied; they were first analyzed and verified in FEA/CFD before proceeding to qualification testing to provide a greater chance of passing the test on the first attempt, thereby reducing the development time and cost spent on test iterations.
The new gravel-pack enhanced shunt-tube system was successfully pressure and erosion tested on the first attempt. The full system integration was successfully completed with no delays or redesign required of the enhanced shunt tube or the packer, enabling the rapid development of the high-pressure bypass system. A multizone openhole gravel-pack completion was installed successfully in the field with the enhanced shunt alternate path tube (ESAPT) screen, high-pressure shunted mechanical packers (SMPs), and shunt-tube isolation valves (STIV) to provide an improved operating pressure envelope and erosion tolerance. The high-pressure SMPs help provide an integrated service—sand control pumping, openhole packers, and shunt isolation technology to reduce capital expenditures by reducing rig time and well count, especially in deepwater wells.