Subsea System Engineering and Operations Consulting

Posts by Brian Saucier

Global Riser Analysis – “Creating a Bridge between Riser Analyst and Operational Consultant”

Key Messages of Blog:

  • Providing Operational input (**)  to support the analyst create the GRA model is essential and can result in lower cost , and improved quality of results.
  • System boundary conditions between riser /landing string need to be defined early to ensure GRA analysis is accuracy
  • Understanding Subsea Equipment functional and structural capacities factor into GRA and adjustments to operability ranges for various uncontrolled events like weather , sea state and currents.
  • End user should have a quality program to ensure that GRA model accurately depicts the “system” which includes the MODU, Riser / landing string, and compensation systems.
  • Assisting the riser analyst understand the significant aspects of the GRA model and ensure that boundary conditions and constraints are identified working as a team will deliver the best overall result.

Open water deployed Completion and Work-over Riser systems (CWOR)  and Specialized Landing strings with SSTT (Subsea Test Trees) run inside Marine Drilling riser systems are two modes to establish bore access to a subsea production tree.   Deployment is either from a MODU or MSV vessel with motion compensation hoisting systems to decouple vessel heave from the riser or landing string.

Riser analyst are often contracted to provide a global riser or landing string analysis which defines allowable operational envelopes for the completion and intervention system.  A typical challenge is many of the riser analyst do not have full understanding of the offshore boundary conditions and constraints and need technical / operational input from operator / consultant (eg DeepMar).

Creating a global model of the subsea equipment, wellhead , Subsea tree and riser  with appropriate stiffness factors at each transition is vital to ensure screening results are estimated accurately.   Additionally, building an interface model with the vessel compensation system to ensure stiffness of compensation during heave, stroke limits , and offset limits are established to ensure riser does not contact MODU /MSV hull all are contributing factors in the GRA analysis.

Typically the end user (eg Operator) has to provide oversight to ensure appropriate boundary conditions  (e.g.  accurate compensation stiffness factors, soil stiffness factors, specific to the well)   are key factors in the analysis process.   Offering practical and operational guidance early in the build of the GRA model can be invaluable and result in an overall lower cost solution. Training and mentoring analyst to improve operational boundary condition understanding  is essential to creating an analytical tool with value.

** DeepMar has provided riser / landing string Design and Operational Assurance service on behalf of major operators to improve safety and operability.

“Stuck Packer during Subsea Completion Installation” – Recommendations

Background

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.

Offshore rig sunset

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.

Recommendations

  1. Leave a full joint of pipe above packers to allow for cutting, without having to cut control lines.

 

  1. 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.

 

  1. 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?

 

  1. 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?

 

  1. 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.

 

Summary Points

  • 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.

 

Subsea Riser Operability – What is it and Why is it important ?

What is an Operability Plan ?

An Operability plan is a operational document bridging output results from global riser analysis and/or testing phase of the various system components to deliver a set of “operability curves” – establishing boundary limits for a specific vessel, riser system, dynamic metocean environment and associated well system.  Understanding of such structural and functional limits are especially critical to manage risk given such  safety functions are barriers impacting well control or well containment.

Operational curves should illustrate limits for various weather conditions related to floating vessel offset, riser tension, Internal pressure, Hydraulic response times (eg latency time to disconnect and appropriate closure sequences -ESD/EQD).  The plan should include  weak point analysis , leakage /functional and structural limits to ensure field operations personnel can manage surface offsets to maintain adequate safety margin of equipment for planned and unplanned DP events.

The Intervention Engineer is typically challenged to consolidate this complex data set and create a functional operational plan.

The following are selected areas such as :

  • Loading conditions for the riser system to evaluate both planned and unplanned conditions
  • Vessel Response to normal, extreme and accidental Weather/ current limits ,
  • Vessel response  conditions when the vessel is connected/disconnected to subsea well assets,
  • System control logic, shut in sequence  and critical function latency time to compare to vessel drift rate to manage risks while connected at extreme and accident offsets.
  • Process should ensure all the assumptions, analysis results compiled are simplified for field personnel to manage (eg Watch circle),  Competency Training of key operational personnel.

Depending on type of MODU (Mobile Offshore Drilling Unit), when a DP (dynamic positioned)  MODU is connected to a subsea asset, the Global operability analysis and plan shall include an unplanned DP drive off / drift off event as contingency to normal operations.  Many reasons may cause a DP event to occur  and such reasons are outside the  scope of this blog.

Note: Links below offer graphic “Example” illustrations to be used for reference only.

Reference Link : DP Operations Guidance

General Description – Subsea Riser System

The System functions as the primary fluid conduit and provides structural attachment between the well and surface vessel comprising of  many components and sealing elements    Such include:  vessel /MODU, riser or landing string system, control system which are integrated and managed by field operations personnel through a comprehensive Operability Plan across uncontrolled weather events.  Creation of the operability plan is one of the most important tasks needed to ensure “The System” can be deployed and provides the functional connection within design and operational limits per the given environment.  The safety components require both structural and functional limits to ensure well bore isolation is achieve at extreme and accidental loads.

Selected Subsea well  intervention operations  require attaching a tubular conduit between a dynamic vessel (eg MODU) and the seafloor or subsea well.  Connecting between the surface floating vessel (MODU) and the seafloor can occur in multiple ways.  Deployment in open water , it may occur using a completion work over riser (CWOR), or through a Marine Drilling riser using a dedicated Landing string as part of a Subsea Test Tree system.  Reference Link – Subsea Riser Connected to MODU.  The illustration highlights the impact of change to surface nominal position when connected to subsea asset.   Surface position of the MODU or MSV (Multi-Service vessel ) can be  caused by loss of Dynamic Position signal, loss of power resulting in limited thruster power to hold position for a given weather event, or limits of riser and disconnect functionality.

NOTE: For Reference an Engineer may reference DNV – RP – H101 for more information to consider when evaluating DP system risks.

Output from Analysis – Station keeping

Global systems analysis is generated within the engineering phase using specific riser component testing data, MODU data and environmental inputs to evaluate selected operational load conditions.  The intervention engineer should fully understand such systems analysis,  performance limits, and  failure modes to ensure appropriate watch circle envelope is generated and communicate safe operational constraints.  Reference Illustration of Watch circle Graphic

The operational plan must consider a loss of station keeping condition as part or the design and global analysis program for a given riser system, while maintaining functional and structural integrity  and establishing critical barriers resulting in control of the well.   Key elements of an operability plan includes a safe shut in – disconnect sequence / well control strategy, while managing offset and riser working stress conditions.   Watch circle envelopes graphically illustrate boundaries which require action to be taken as offset may increase from nominal well center surface position.    The typical watchcircle uses (GREEN – SAFE), (YELLOW – Take Appropriate Action), (Red – Disconnect) concentric circles to aid field management as to when to take appropriate action at the appropriate time.  Additionally, using drift rate prediction curves, the envelope should highlight safe shut in periods if loss of power or other unforeseen failure events may result in uncontrolled surface offset.

Other selected factors which impact envelopes are:

  • MODU Drift rate (caused in the event of failure of power or thruster system for various weather conditions),
  • Riser Internal Pressure and Tension Conditions,
  • Current loading which may result in lowering fatigue life of riser system
  • Current loading which may impact control functionality and reliability
  • Knowledge of Integration of hardware and control system.  The output of various analysis both structural and hydraulic response limits , static and dynamic  loading conditions, control system response time predictions are input elements to the Watch circle Envelope.
  • Pre -Engineering: Global Analysis  engineering combined with test qualification data  used to define functional (eg Leakage)  and structural limits (eg Failure)  of various system component in the primary load path.

Comprehensive Elements of Plan

Various load conditions should be pre-defined which typically are  changes in pressure, tension, bending caused by offset of the vessel, or operational changes.  Conducting analysis to simulate the various system limitations across a range of loading conditions is critical.  This complexity both on the design of the riser & control systems response times evaluated within  vessel drift limits  is vital to achieving desired operational limits within the prescribed safety envelope.   Changes to vessel infrastructure , global  regions , various loading conditions impact offset conditions and limits and directional shape.

Creating a comprehensive Operational  plan, should be an iterative process both with Engineering and Operations to ensure proper training and understanding of the limits of the analysis are conveyed to the field.   The operational plan is complex and shall  incorporate  a range of environmental conditions, equipment performance limits based on load cases, control response times, vessel response motion characteristics all built into simplified procedure resulting in the formation of a safe operability plan with clear performance limitations of each component in the primary load path.

How can DeepMar Consulting Assist ?

DeepMar Consulting has extensive experience in systems engineering and operational planning to many clients, which conduct riser based operations in offshore environments.  This blog is intended to offer a subsea engineer the basics and  illustrate selected Operability elements to create safe and executable  offshore  plans, while offering useful links to reference which aid in improved operational safety , reliability and efficiency.    To manage such complexity requires in depth front end planning, multi-team buy-in (eg Engineering and Operations)  and continuous attention to understanding the performance boundaries of equipment to control risks across an array of conditions.

We welcome and look forward to your comments on the blog …

 

Is it Validate or Verify ?

 

I often have discussions with peers and co-workers about whether we should validate or verify some process or activity.

 

I find there is significant confusion as to what these terms actually mean and what an Customer and/or Third Party should be doing.

 

Since I recently had one of these discussion, I thought I would share my thoughts.

 

The Wikipedia Definition states….. Verification and Validation are independent procedures that are used together for checking that a product, service, or system meets requirements and specifications and that it fulfills its intended purpose. These are critical components of a quality management system such as ISO 9000.

 

Common definition can be expressed as:

  • Verification is intended to check that a product, service, or system meets the design specifications. This can also be the Customer’s specified requirements.
  • Validation is intended to ensure a product, service, or system meets the operational needs of the user.

 

Here’s a simple way to look at it. Verification comes before (and after) Validation because you can’t successfully Validate a process or product until you have Verified that it meets the established design criteria or requirements….and then you can Verify that it has been Validated….and then you can Validate it was Verified.

 

Perfectly clear.

 

Another common way to determine the difference would be that Validation answers “Are you building the right thing?” and Verification answers “Are you building it right?”

 

Where “Building the right thing” refers back to the user’s needs, while “building it right” checks that the requirements  are met.

 

So with that in mind, here are a few examples on how “I” would use these terms……..

 

When it comes to specially engineered equipment, I will

  • Review the process of how the manufacturer Validates the design
  • Utilize the services of a Third Party Quality Assurance Inspector to Verify that the manufacturing control features are being performed

 

I also often use the services of a Third Party Quality Assurance Inspector to Verify that a contracted Service Provider is following an approved Service Plan (as in API Q2).

 

I have also used the services of a Third Party Quality Assurance Inspector to Validate that an Equipment or Service Provider has met the requirements of their Quality Management System.

 

I may also Validate that the Equipment or Service Provider has a process of Verification in place that ensures compliance to agreed terms.

 

I will Validate that an Equipment provider has a plan for maintaining traceability – I will then Verify that traceability was maintained during the Manufacturing Operation.

 

Note: This blog was contributed by Jim Hood and posted on DeepMar Consulting Website.

Knowledge Footprint

We are in a challenging market…….is this really the best time for training? I would argue that it is an Excellent time to consider training and increase you Core Staff’s “knowledge footprint”.

It’s common that when times are good – we are too busy to train and when times are bad there is no money to train. Perhaps we need to rethink this position.

Too many times training is simply looked upon as “Cost” instead of either a strengthening of core capabilities or adding a new dimension to an employee’s general knowledge of a product or service. However, these are great reasons for providing training to key employees during this industry downturn and will allow an organization to operate in a leaner environment moving forward.

The key is to target training that adds value for the person’s position or job responsibility. To design a training program for a team of Drilling Engineers, the training should not be to a level in which they become proficient in services or tasks they would not normally perform – but rather provide them with targeted training to understand the fundamentals of those services or tasks so they can better communicate with those departments or service providers on what they need from them to accomplish a task or deliver a project.

Training in Quality Assurance is an area that can be beneficial.

Let’s use “Auditing” for example. An overview of what the Auditor does and what resources they use would provide benefits to the Engineer with a better understanding of the advantages, expectations and limitations of an “Audit”. This would allow the Engineer to broaden their core competency by being able to better communicate the need and objective for an Audit of a selected Supplier or Service Provider being performed by a Certified Auditor. The Engineer does not need to reach a level of proficiency as an Auditor.

“Inspection” is another area where fundamental training might be beneficial. The word “Inspection” needs further definition in order to communicated properly. For example, the Engineer is not likely to actually perform Magnetic Particle Inspection Services so a complete “Level II Magnetic Particle Class” is add value to their core competency as much as a comprehensive understanding of the Method, how it is performed, personnel certification requirements, and the distinct advantages and disadvantages associated with inspecting the equipment provided by the Suppliers and Service Providers they engage in performing their jobs.

I often say “people generally don’t know what they generally don’t know”.

Targeted training will allow a Core Staff to have a larger “knowledge footprint” in their specific job responsibility or career. It supports better communication and allows for the possibility of working in a leaner environment. It’s looking at the “bigger picture”. This is different than training designed to enable someone to perform a specific job.

We can all benefit from a broader “knowledge footprint”. If your specific job responsibility is Purchasing, Engineering, Accounting or some other critical path function within an organization – any training you receive should increase your “knowledge footprint” and enable you to communicate more effectively promoting continued and future success in your job.

In order to target the right training that will broaden the “knowledge footprint” for a person or department a competency assessment needs to be performed. These assessments can be as complex or as informal as needed to generate the right discussion on where targeted training is needed.

As we prepare for what many believe is a new “normal” in our Industry, training has to be part of the strategic discussion of how we do business. But when the discussion starts to develop don’t let it shift straight into “cost”.  Make it part of the plan to deal with the changes we are all facing. Shift the discussion on how to increase our “knowledge footprint”. It will increase efficiency and reduce cost.

Contributing Subscriber : Jim Hood

ASME Training : Bolt Qualification “New” Program

Industry has experienced subsea equipment failures with bolts.  The BSEE link highlights the work conducted industry related to such failures.

https://www.bsee.gov/what-we-do/regulatory-safety-programs/offshore-safety-improvement/bolt-and-connector-failures

Bolting integrity and competency of technicians  for all subsea and surface application  flanges has been raised as a major issue in recent years. Understanding the quality of bolting materials and associated torque preloads required to meet pressure and tension /bending limits are essential to any flange connection.  Improved quality, reliability , integrity and Safety through Training and improved competency.

ASME recently developed a   “Training” program for bolting and can be referenced at :

https://www.asme.org/shop/courses/asme-training-development/bolting-specialist-qualification-program

The Training program may offer additional quality assurance to achieving bolt integrity to your next project.  Both links offer access to value resource data for this topic.