Installation of subsea completion systems inherently have high risk related to probability of getting stuck prior to reaching the target zone or production objective. The risks of getting stuck are due to deviated wellbores , tight clearances between production equipment and casing, unplanned forces of drag and frictional effects which are difficult to model.
Recognition of such risks early and creation of front end contingency plans during engineering phase can mitigate and manage risk, and reduce the repair and recovery cycle time if the packer is prematurely set . Conducting an indepth cost benefit analysis, to investigate minor completion enhancements can offer improved mitigation strategy and contingency alternatives to such a high risk event. Understanding the risks, consequences and creation of risk mitigation plan for stuck completions and premature setting of packers should consider development of “contingency plans” during the planning phase. Seeking a decision on low cost capital improvements to the completion, may provide quicker solutions and alternatives if the stuck packer event occurs.
” Pre-investment in high consequence type failures is always a debate. Often rigorous cost/benefit analysis is typically not considered or identified, therefore pre-investment is overlooked resulting in higher well delivery costs.”
It is not implied that the additional safeguard equipment installed is the solution to every potential failure event, however the risk and ranking of selected events warrant such a consideration give the high consequence cost and delay or potential loss of well consequence events which may occur. For novel equipment or equipment which has new functionality always carries some additional risks. Evaluation of enhancement should be evaluated within a cost benefit analysis so that risk and mitigation strategy is equally weighted.
Deepwater subsea completion installation from a DP MODU carries both controlled and uncontrolled risks. Risks which are typically mitigated through proper procedures, testing of equipment; however project teams typically do not recognize many low-cost, pre-investment opportunities focused in selected tools/equipment configurations which offer high value and rewards during installation and future intervention operations. Teams should focus on identification of the “low hanging fruit” in terms of tools, processes to simplify future unplanned operational contingencies.
The operational event outlined below may offer a case scenario which illustrates the importance of early project primary and contingency planning, illustration of pre-investment of engineering and capital equipment offering solutions and recommendations to promote faster recovery at lower risks and cost. The operational event described below illustrates a realistic scenario and maybe a useful tool to create awareness at the planning phase to mitigate such an event.
Operational Event – What do we do now!
Scenario: When deploying subsea completion and fully transferred to landing string the Production Packer /upper completion sticks and “Unable to Deploy Completion to target depth”
- What are your options?
- What contingency options have you planned for?
- Do you have contingency plans in place, tools on location, etc.
This blog illustrates a scenario which may occur during installation of subsea completion through a liner top and provides several recommendations for consideration.
It’s 1:35 a.m. your cell phone is ringing and awakes you. The rig is calling, your mind starts going through the operations that are currently taking place on the rig, running upper completion, should be around the liner top. You answer, it’s the lead well site leader, the production packer is stuck after being worked through the liner top. Now the packer will not move. You mind is running through the completion jewelry, gauges just above the packer, and control lines to each of the two downhole gauges, clamps holding control lines. The well was drilled with a very tortuous path, having several sever doglegs, resulting in variations of pickup and slack off weights of 150,000 lbs.
Do you have Adequate Recovery Options?
How do you recover? Incorporating front end contingency intervention planning early in project planning cycle, could be the difference between a few days of recovery or a few weeks of recovery.
When planning your completion contingency risk management should be worked and mitigation plans developed. Evaluation of how you would recover, steps, tools, procedures, risks given the change away from primary operational plan all should be addressed. Establishing a preliminary recovery plan for selected events and communicated to field operations can make the difference to ensure success. Build these recovery options into your completion where possible.
Downhole Fishing Plan – Assurance to Gain Accessibility
During the initial completion design a “fish-ability” review should be conducted both during initial and late life intervention /work-over operations. The following are a few recommendations to consider when planning your next completion so that when you get the “middle of the night” call the solutions will have already been planned.
- Leave a full joint of pipe above packers to allow for cutting, without having to cut control lines.
- If you’re running a cut to release packer, how are you locating in the 18” cut window?
- Consider incorporating a nipple profile just above the packer or a crossover with a slightly restricted I.D. to serve as a no -go .
- Make sure the distance from the top and bottom of the cut window to the land out point are measured and documented for future use.
- Contact the wireline company and get the cutting BHA now to insure there is adequate room to land out and cut.
- What type cutter are you running to cut the tubing above packer if need?
- Did you consider nipple I.D.?
- What is the O.D. of that cutter?
- Will the cut require dressing to be latch with an overshot? Can the cutter cut if the tubing string is in compression?
- How much debris will the cutter leave?
- Will debris affect my completion?
- How do I hold open the safety valve if the control lines are damaged?
- Does the hold open sleeve or lock out device restrict the I.D.?
- Can I still get the required wireline tools through the safety valve lock open device?
- Other considerations
- Are all completion components fish able?
- Can I burn over the packer?
- What is the maximum casing wall lost before the well integrity is compromised?
- Well control, a plan should be in place to secure the well at any point.
The recommendations are general and offer risk mitigation points for team to consider during planning to have the “contingency” action plan in place to aid in a quick recovery. The more preplanning you do, the easier it will be to deal with that early morning call.
- Develop Realistic, contingency plans during the design phase. The use of “what if scenario’s to replicate the conditions and constraints are important factors towards full understanding recovery options.
- Evaluate and define the operational limits of the system. Identify areas which offer a lower risk profile and require little investment.
- Identify any “new innovation” or change to tools which cause inherent higher risks.
- Perform Testing and functional simulation of equipment to replicate insitu conditions. Examples are tubing cutters, specialized plugs, and/or location tools. Understand all tight interfaces which are flagged to be problematic and make information available to field personnel. Industry can do more with computer simulation provided the boundary conditions and constraints are adequately modelled.
- Build the design and operational program and take to the field to ensure onsite personnel recognize the risks and have pre-worked the options to shift towards recovery as soon as practical.
This blog is for informational and reference purposes only jointly written by Brian and Lynn Saucier. Brian and Lynn have a combined 75 + years of experience in subsea engineering and deep water operations. We offer this blog to assist any team during planning and execution of subsea well installation and operations. We welcome comments and feedback to the blog post.