Economic Report 2011

Case Study: Using Down-Hole Flow Equipment with Intelligent Electronic Technology to Reduce Interventions during Complex Subsea Well Operations and to Enhance Safety

figure 53 300w jpgRed Spider Technology, a well services specialist based in Aberdeen, provides clients with the ability to programme down-hole flow control valves, using remote control open and close technology, to monitor and respond to actual conditions in a well. This reduces the need to implement well interventions or use control lines which are time consuming and expensive. Clients can programme the tool, known as eRED®, to respond to a number of activation “triggers” such as time pressure windows, temperature and hydrostatic pressure.

Requirement

BP had used an eRED® down-hole valve on several of its platform and subsea operations in the UK and Norway as an intelligent computer programmed tool to equalise pressures during well interventions.

As a process, well interventions can be labour intensive and time consuming requiring teams offshore to erect scaffolding, carry out heavy lifts and rig up surface pressure control equipment which introduces additional risk and HSE exposure. These operations can be delayed by difficult weather conditions, leading oil and gas operators to seek technology that enables them to carry out completions more safely and which may reduce, or eliminate, the need for well interventions.

Solution

With experience of deploying eRED® down-hole valves on previous intervention projects, BP saw the potential for adapting the tool in its Machar field. Machar is a subsea well which is tied back to the ETAP platform (Eastern Trough Area Project, operated by BP), which produces oil and gas from one of four separate fields, Marnock, Mungo, Monan and Machar, all part of ETAP.

For the well completion on Machar, BP first executed a lower well completion and then, for the upper completion, used two eRED® valves, instead of the traditional plugs or barriers normally used by the industry. Each valve was programmed by BP to respond to its own unique command of a predefined pressure being applied over a specific time period. The valves were pre-installed in well tubing, one as a deep-set barrier below the production packer while the other was located higher up in the tubing hanger, and fully tested onshore prior to being shipped out to Machar.

Method

BP carried out the upper completion of the well with both eREDs fully open allowing fluid to bypass the valves and pressure to gain access to the lower completion for well control. With the completion at depth, the tubing hanger was landed and locked in place. In order to pressure test the production packer, BP instructed the deep-set eRED valve to close with a pre-programmed pressure and time command of 750 psi (500-1,000psi window) applied to the tubing for ten minutes. A delay of five minutes was programmed into the tool (to allow tubing pressure bleed down prior to the eRED closing.)

BP set the production packer hydraulically by applying pressure against the deep-set eRED valve, but the first attempt to pressure test the production packer was unsuccessful. Having programmed the eRED to respond to repeating triggers, BP opened the valve with the same pressure and time command of 750 psi (500-1,000psi window) but this time excluding the five minute delay. After closing the eRED valve once more BP was then able to achieve a successful pressure test.

The eRED in the tubing hanger was then instructed to close with its own pre-programmed pressure and time command of 1,750psi (1,500-2,000 psi window) applied to the tubing for ten minutes, with a time delay of five minutes. With both eREDs closed, providing a fully testable dual barrier, BP was able to remove the drilling blow-out preventer as well as installing and testing the subsea tree.

On completing these operations, BP remotely opened the tubing hanger eRED using its command trigger. Positive feedback that the valve had opened successfully was observed at surface in the form of a tubing pressure drop and the same process was repeated successfully for the deep set eRED.

Outcome

During the operations to prepare the Machar well for production, BP was able to carry out multiple tests using eRED technology to eliminate a total of six deep and four shallow wireline runs, so reducing exposure to risks associated with rigging up slickline for interventions and exposure to potential delays caused by adverse weather offshore. Pre-installation of the eRED valves onshore also enabled BP to reduce slickline runs from ten to two minimising risks to personnel as well as time spent operating equipment offshore.