Tuesday, July 31, 2018

Questioning the Way We Drill

Since June 1993, a team of engineers from drilling contractor Sedco Forex has been reviewing a range of issues, from the organization of drilling activities to optimum rig design. By looking at the whole picture, the team aims to develop an efficient drilling rig with a minimal environmental impact that may be operated by fewer, aand more skilled people.

 The cast normally required to drill and complete a well involves a host of different companies. Each subcontractor comes to the rig site with dedicated equipment and personnel, requiring mobilization, demobilization and accomodation for all those involved. Therefore, the key to streamline a rig is to reorganize operations, change traditional practises and job descriptions, and reallocate responsiblities. After this, packages and tasks may be restructured and amalgamated.

In the past, oil companies tended to control the hiring and managing of contractors and subcontractors. However, recent reappraisals of their core activities by a number of oil companies have led to a change in the way some wells are drilled. For example, in what are called integrated contracts, the role of organizing the subcontractors may be devolved by the oil company to one of the contractors.

Integrated contracts cut down on the need for the operator to supervise subcontracts, and improve synergy between the participating companies. However, in their reappraisal of the drilling process, the Sedco Forex drilling engineers have taken a more radical approach. For example, all mud functions may be integrated so that mud mixing and cleaning, and cutting disposal become the responsibilities of a single organization - as opposed to today arrangement of splitting the work between the mud engineer, the rig crew and several specialist ( to provide extra cutting-cleaning equipment, for example).

But with the aim of creating a fully integrated rig team, the proposals cut even more deeply through the divisions created by traditional service company demarcations. 

The team has assembled a set of reorganization proposals that may be adapted to specific client programs.
  • Merging cement and mud activities - By handing over responsibility for mud and cement to a single fluids engineer, personnel and equipment may be shared.
  • Improving the synergy between mud engineering and mud logging- Having the mud logging engineer - or geologger - share an office/laboratory with the fluids engineer encourages cooperation and ensures consistency in fluids and formation information.
  • Integrating the measurement-while-drilling (MWD) and wireline logging functions- The same personnel may run all directional, density, resistivity and porosity logs whether logging while drilling or on wireline. However, more sophisticated wireline logs would probably involve a specialist logging engineer. The driller and the drilling crew may assist in running the wireline tools using a logging unit that is an integral parto of the rig.
  • Combining the driller and directional driller's job- Giving the driller responsibility for directional drilling means that there is constant directional monitoring throught drilling.
  • Implementing a single maintenance team- Having all the equipment maintained by a dedicated maintenance crew results in improved consistency and better planning.
  • Cross training of all rig personnel- Increasing the skills of all members of the work force will improve synergy between activities. Not only is the driller trained to carry out directional drilling duties, but also the assistant driller and floor crew should be able to assist in logging, cementing and mud logging operations.

 If all these  changes are enacted, the crew needed to drill a well may be cut by approximately 30%. Support facilities such as accomodation and catering may also be downsized accordingly.

"What kind of wells are needed?"

Traditionally, wells have generally been completed using a casing/liner with a diameter of 6 in. [15 cm] or greater. However, an increasing number of slimhole wells is being drilled. Although there is no real standard for defining slimhole wells, they are typically completed with 3 1/2 -in. casing in 4 3/4-in diameter open hole.