Deepwater Well Delivery

Deepwater Drilling Operations are generally defined as taking place in water depth in excess of 1,000ft (330m).  These conditions represent a challenging and rapidly growing operating environment in many areas of the world.  With increasing depth below the mud-line, many of these wells are also High Pressure High Temperature (HPHT) wells. 

 

New build rigs as well as upgrades continue to leave shipyards to service this growing market while equipment manufactures and service providers continue to invest heavily in associated technological innovation.

 

With the cost of running a deepwater drilling operation running to well in excess of $1 million a day it is critical that a high level of competency exists amongst all personnel associated with the delivery of a deepwater well.  This can prove a challenging objective in a rapidly growing workforce – for Operators, Drilling Contractors and Service Companies alike.

 

This course provides participants with a wealth of practical and operationally focused knowledge.  It builds critical skills in well delivery with an emphasis on the operational aspects of well delivery in deepwater.  The course addresses:

• Operational Planning

• Rig Operations

• Performance Optimisation

• High Reliability Drilling Practises

• Deepwater Well Control

 

Scenario Based Training - The course can be delivered as an in-house course for rig teams during rig start up and/or preparing for a critical deepwater well.  Such in-house courses typically include the well modelled on a Drilling Systems Drilling Simulator with a number of scenarios modelled during the course.  Such sessions facilitate the evaluation of command and control capabilities and the development of Crew Resource Management skills.

 

Competence Development

At the end of this course delegates should be able to:

 

1. Explain the differences in pore pressure and formation strength characteristics associated with deepwater environments

2. Explain and describe the challenges of well control in deepwater environments from pressure prediction, detection and well control procedures.

3. Recognise the operational challenges associated with shallow water flow and shallow gas in deepwater

4. Understand the different classes of DP vessel and how they can mitigate the risks associated with “Drive Off”

5. Can explain equipment requirements, roles and responsibilities associated with Emergency Disconnect systems

6. Understand the differences in well design between Deepwater and conventional wells and how technologies such as expandable tubulars, Surface BOP systems, Managed Pressure Drilling and Riserless Mud Recovery can help to close the gap

7. Explain the impact of large temperature gradients on casing loads including trapped annular pressures and techniques for mitigating trapped annular pressure

8. Identify rig equipment critical to deepwater well delivery and select rigs suitable for deepwater drilling operations

9. Explain how ballooning / wellbore breathing can be identified and managed

10. Describe what is meant by fingerprinting and develop rig procedures to use fingerprinting effectively.

11. Explain the importance of Cement Placement for shallow water flow control

12. Describe what hydrates are, where they can form, what problems they can cause and how they can be prevented and cleared

13. Appreciate why crew training and communication are critical aspects in successful deepwater well delivery

 

 

Course Content

The following subjects will be addressed during the course:

 

The Deepwater Drilling Environment – this session examines deepwater locations and geology and the particular challenges this generates including Metocean conditions, weak mudline formations,  rapid overburden deposition  and resultant under-compaction problems such as shallow water flow,  temperature contrasts, rapid increase in pore and fracture pressures  and sub-salt issues.  The session also looks at the development of deepwater drilling practices and technology including future trends.

 

Operational Planning – this session focuses on the drive for operational effectiveness through technological innovation including opportunities for concurrent operations facilitated by dual activity / multiple work centre drilling units.  It considers also how operational lead times demand longer decision making cycles, particularly for critical operations such as running / retrieving BOPs, running and cementing casing strings etc. 

 

Deepwater Drilling Rigs – This session looks at how rig capabilities and selection are impacted by Metocean conditions and considers how different vessel configurations can effect  Stability and Loading, Station keeping and DP operations, Dual Activity Centres.  BOP requirements for deepwater operations, particularly for DP vessels is addressed as are critical rig capabilities inkling drilling fluid management, Variable Deck Loading, riser management and drilling process mechanisation and automation.

 

DP Operations  - This section examines Dynamic Positioning.  The equipment required to maintain position without mooring in deepwater is explained.  The different failure modes of DP and how they are mitigated by equipment specifications on different classes of DP vessel are explained alongside the concepts of watch circles, excursion rates, maximum riser angles, drift off and drive offs.  Operational procedures and DP management as well as alarm settings and Emergency Disconnect protocols with and without shearable pipe across the BOPS is also addressed.

 

 

Drilling fluids and cement –  This session looks at issues related to drilling fluids and cementing experienced in deepwater operations.  For drilling fluids these include managing the logistics of the riser mud volume, achieving adequate hole cleaning with tolerable levels of ECD, the effect of both high and low temperatures on fluid rheology, density and volume and challenging conditions in long kill and choke lines.  For cement placement, the challenges include low temperatures and formation strengths at and below the mud line, combating shallow water flow, achieving conductor pipe mechanical stability and achieving good zonal isolation across multiple casing strings.

 

 

Deepwater Drilling Practises – This section examines the drilling practises required for high reliability well delivery in deepwater.  It considers procedures that can mitigate problems associated with high mud gradients / mud rheology, narrow margin environments and thermal effects.  It also introduces the concept of the “Safe Drilling Checklist”.   Key areas include:

 

• Conductor Jetting – softer mudline sediments can permit and require surface conductor strings or foundation piles  to be jetted into the ground rather than the conventional drill and case procedures. This session examines critical design parameters and operational practises to successfully jet conductors

 

• Expandable Pipe – with multiple casing seats driven by the ramping up of pore pressure and narrow margins for formation strength, expandable tubular technology offers potential for planned or contingency casing seats without reducing the final hole size at TD to the point where the production or evaluation objectives cannot be achieved.   This session looks at the opportunities and limitations of the different versions of expandable technology.

 

• Casing while Drilling – Drilling with casing, either full strings back to the mud line or drilling liners, can help to eliminate surge and swab problems as well as bore hole stability issues in sub-salt regions.  This session looks at the equipment and operational practices as well as the limitations of this technology in deepwater operations.

 

• Riserless Mud Recovery Systems – once the conductor or surface casing has been set, conventional drilling sees mud returns up the riser.   Even with modest mud gradients,  this column of fluid generates hydrostatic pressure close to the formation strength in shallow formations below the mud line requiring multiple casing shoes over a short distance.   This section looks at how riserless mud recovery systems can  address the problem.  It examines the rig requirements, operational procedures and practical  limitations of this process.

 

• Managed Pressure Drilling (MPD) -  MPD, including dial gradient drilling, offers solutions to a number of the challenges of deepwater  well delivery particularly where HPHT conditions also exist.  MPD permits lower fluid gradients to be used, facilitating a reduction in the number of casing strings required.  This section addresses the benefits of MPD operations and examines the equipment and practises for its implementation in Deepwater wells.  It includes Dual Gradient Drilling, Dynamic Anular Pressure Management and Pressurised Mud Cap Drilling - particularly to manage hazards associated with pre-salt carbonates.

 

• Surface BOPs – conventional deepwater drilling operatons are conducted with a sub-sea BOP and a low pressure riser.  This presents operational and well control challenges with long kill and chokee lines and the operational practices crequired to minimise the risk of gas laden fluids entering the lowe pressure riser.  This section examines the equipment and practises developed for benign areas for the use of a surface BOP, high pressure riser and sub-sea emergency disconnect systems.

 

 

Primary Well Control – The prevention of kicks by maintaining adequate BHP to overbalance permeable formations is a fundamental goal when drilling any well.  It is complicated in deepwater wells due to the effect of temperature changes on drilling fluid throughout the wellbore linked with the prevalence of oil based drilling fluids.

 

The narrow margins between drilling fluid gradient and formation strength in deepwater wells, particularly in the area immediately below the mud line, makes control of excessive wellbore pressures equally critical.  The effect of temperature and pressure on drilling fluid density, the importance of ECD management, and use of PWD is explained. The use of high reliability operational procedures to minimise surge and swab effects is emphasised. Kick tolerance and gas behaviour is discussed in terms of the effects of temperature and the importance of monitoring gas while drilling is explained.  Ballooning, breathing and supercharging will be explained along with techniques to differentiate between these effects and loss of primary well control.

 

Fingerprinting – the impact of temperature in fluid density and volume downhole means that conventional well control signals are less reliable in Deepwater operations.  Uncertainty about the stability of the well can result in significant non-productive time.

 

It is critical  to understand the normal behaviour of a well such that abnormal behaviour can be rapidly identified and reacted to.  Proactive information gathering or “fingerprinting” prior to and while drilling deepwater sections achieves this.  The array of data to be analysed and modern mud logging techniques that can be used  are addressed.

 

Secondary Well Control  – Comprehensive knowledge and sound skills in the principals and practises of well control are critical to Deepwater operations.   This section addresses pore pressure prediction and narrow margin environments and their profound impact on kick tolerance.  The origin of shallow hazards  and an explanation for narrow pressure margins between pore and fracture pressure is covered.  The causes of kicks and kick detection are addressed including early kick detection technology. 

 

Practical well control procedures based on real-world experience are discussed to combat influxes taken with the drillstring on bottom, off bottom and with the drillstring out of the hole are reviewed.   These include driller’s method,  volumetric method, bullheading, and the combined volumetric and stripping method.    Particular focus is paid to friction effects in long kill and choke lines and how BOP mounted temperature and pressure gauges can be used to improved control of BHP.  

 

Gas solubility in Oil – This session considers how the solubility of gas in oil based mud, base oil and crude oil cam create problems in detecting and managing influxes.  It presents the concepts of gas saturation, absorption and release rates and wellbore pressure responses following breakout of gas in the wellbore.   Crew preparedness for gas solubility issues is also addressed

 

Kicks and Losses – Given the narrow margin between formation pressure and fracture pressure in deepwater wells, the situation may arise where there are simultaneous influx and losses leading to underground flows. The causes and treatments for underground flows are described and explained.

 

Hydrates – Hydrates are a particular problem in deepwater operations due to the low temperatures encountered at the mud line.  These can form inside and outside the BOPS, causing a number of operational problems.  This session examines what hydrates are, how and where they can form and the risls the present.  Techniques to prevent to formation of hydrates forming and also to eliminate hydrates once they have form are addressed.

 

Teamwork and Training – competence, teamwork and communications between well delivery team members is critical to ensure the safe drilling of Deepwater wells.   This section examines how rig team communication and performance on critical wells can be enhanced by processes such as “Drilling the Well on a Simulator”