DRILLING CONSORTIUM—2 (Conclusion): Drilling campaign obtains continuous improvement

Aug. 1, 2011
A 3-year exploration drilling campaign run by a well management company for five operating companies saw continuous improvement in operations off Norway.

Bjorn Thore Ribesen
Arild Saasen
Det norske oljeselskap ASA
Oslo

Kjell Arild Horvei
Halliburton
Stavanger

Tove Magnussen

Tormod Veiberg
AGR Petroleum Services AS
Oslo

A 3-year exploration drilling campaign run by a well management company for five operating companies saw continuous improvement in operations off Norway.

This concluding part of a two-part series will discuss the integrated service provider, logistics, risk management, and technical performance of the campaign. The first part (OGJ, July 4, 2011, p. 72) explained the management system and the health, safety, and environment (HSE) concerns.

Integrated service provider

The drilling campaign used one service provider for the majority of the service work such as wireline, drilling fluids, mud logging, cuttings and slop handling, coring, measurement-while-drilling (MWD), logging-while-drilling (LWD), directional drilling, bits, and cementing. The multiple service award to one service provider presented a variety of technical and commercial benefits such as:

• Alignment of quality and performance goals.

• Dedicated project organization.

• Prioritized service across the entire organization.

• Engineering efforts focus on well target.

• Ownership of project.

The wireline work was subcontracted to a third-party company through the main service contract.

A project team led and organized the different drilling services as an integrated package. Fig. 1 illustrates the project model.

A project manager led the integrated project team and was the main point of contact (focal point) for the different operators in the rig consortium and for the well management company and drilling contractor. This short communication and decision route allowed more effective operations. Key activities conducted included prejob engineering and planning, risk mitigation, logistic coordination, service delivery, and third-party coordination.

The organization had a team of dedicated project personnel with accompanying system and processes in addition to the standard service provider coordinators, such as project manager, assistant project manager, logistic coordinator, HSE coordinator, and product-line service coordinators.

Logistics

A project's success requires the safe movement of equipment and materials to the right place at the right time and in a cost-effective manner. The drilling campaign used a destination-driven approach for project management. The focus was to move all required goods to the location regardless of the number of internal departments involved. Key elements to the approach included organization, communication, responsiveness, and functional competency.

The logistics function was an integrated part of the project organization. A dedicated logistics coordinator was involved directly from the tendering phase in the planning and execution of the project through to end.

The logistics coordinator participated in the twice-daily operational project meeting. Consequently, this allowed the transfer of essential information first hand and without delay, reducing the risk of misinterpretation and enabling service providers to be more responsive to the project. It also allowed the logistics coordinator to work with the various internal departments and consolidate freight movements.

To further provide timely services, project management ran 24-hr, 7-days-a-week logistics with personnel always on duty. The competence and skill of the logistics coordinator ensured success. The role requires knowledge of rules and regulations as well as the different operational scopes to ensure safe handling of materials.

The logistical operation complexity is obvious because of the number of logistical operations within the drilling campaign. Fig. 2 illustrates the total amount of wells, bases, mobilizations, cargoes, weights, and demobilizations during the consortium's operation.

Cooperation

The collaborations among the service provider, operators, well management company, and drilling contractor were central to optimizing the integrated service performance. With no competing elements but a diversity of knowledge and experience, the team presented and used more optimal solutions.

This collaboration allowed the service provider to balance delivery more than through a discrete service contract. The service provider operated the equipment and products within its operational limits resulting in increased operational time and efficiency and less unproductive time.

The consortium management model with short communication lines was effective.

Each product line coordinator received a broader understanding of the total operation and became more capable to recommend optimal solutions that did not conflict with other products and services.

Processes

Each product line or department within the main service provider's organization has processes and procedures for all tasks in the initiation, planning, implementation, and close out of a project. The service company's management system documented these processes and procedures.

A bridging document or work-flow process linked the service provider's processes and procedures to the operator's and well management company's standardized system (Fig. 3). Use of the bridging document allowed the service provider to be represented and involved throughout the different phases of the planning, and to have more influence on solutions.

Risk management

Risk management of the operation is part of the well established processes and procedures for an operation. As described in Part 1, the well management company handled the risk management for all wells drilled.

The service provider's work flow adopted follow-up documents and to-do lists that identified responsible persons and deadlines for each task or item. The service provider brought its experience on transfer and risk identification from internal systems into the well management risk system for each well.

Optimizing across product lines

Throughout the drilling campaign, the service provider systematically, together with the operator, well management company, and rig owner focused on improvements.

The service provider internally had developed systems for all product-line representatives for optimizing their delivery without interrupting other deliveries.

It is common for one or more service deliveries to cause operational conflicts, resulting in unproductive time. The in-place cross product line systems for optimizing and balancing the different product lines reduced the chance of conflicts with the result of increased operational time and reduced downtime for the service provider.

Fig. 3 shows the operational time during the drilling campaign.

Shallow water flow

As in all drilling operations technical and operational incidents challenged the structure of the organization. An example showing how quickly the organization could react to incidents is the shallow water flow in Well 16/1-9, Draupne.

Shallow water flow severely hindered drilling in the exploration well.1 The well had 20-in. casing set above a shallow gas zone. After installation of the blowout preventers (BOPs), drilling of the 171⁄2-in. section started and continued for a few 100 m. A remotely operated vehicle was used routinely to inspect the wellhead.

After awhile, a tiny flow started around the wellhead. The flow increased in strength and later a large washout formed and further drilling was terminated. Most likely, the water flow came from a zone behind the 20-in. casing.

To stop the shallow water flow, it was decided to use grout cement on the outside of the casing. Regular well cements were not desirable because their mineral composition retards curing. The cement selected was standard construction industry cement with a very short curing time.

The BOP needed to be removed before grouting started, so that the well required other barriers for well control. Because of the shallow gas zone beneath the 20-in. casing, the well needed two barriers. Two packers, one drillable and one retrievable, provided the barriers. After removal of the BOP, the grouting operation was successful.

No water flow or gas flow were observed while the cement was setting. Drilling resumed in the 121⁄4-in. section after the cement cured and the packers were drilled out and retrieved.

The operator took an active part in selecting the best solution together with the drilling management team. During this period, the operator had close contact with the authorities and partners to ensure that all stakeholders agreed with the selected method.

The operator informed the authorities with the necessary information regarding handling of the operation in a safe matter, always with the main objective of keeping the well barriers intact. Communication with partners and industry ensured the review with the drilling management team of all previous experiences and best practices in similar incidents.

The project meetings for the following wells decided to continue using rapid hardening industry cement systems for the 30-in. casing.2 The next sections frequently included foam cement for improving well integrity.

The short decision routes in the consortium simplified implementation of technological solutions. The technology provider presented the technology directly to the well management company and operator at weekly cooperation meeting. The meetings recognized that these items would improve safety and thus were implemented.

In a similar manner, the project implemented the use of a riserless mud return system for ensuring safe drilling operation in future areas with potential shallow water flow. A benefit of these systems was the reduction of the affect of the operation on seabed fauna.3

Anchor handling

The use of integrated services from a main service provider did not hinder the use of the intelligent application of other services. Anchor handling is an example because there was no competition to the technology delivered by the main service provider.

The combination of the well management company and the operator, however, did develop an operation based on combining anchor pick up, rig move, and presetting of anchors at the next drilling location.4

Well abandonment

An organizationally more difficult case was the use of alternative methods to conventional plug cementing in abandonment operations.

The traditional plug and abandonment method of exploration wells in the North Sea sets a series of cement plugs to isolate the pressurized zones from each other and from surface. The service provider supplied the cementing services. To increase long-term well integrity and reduce rig costs, however, an alternative method used a Bingham-plastic unconsolidated plugging material with high solids concentrations in the reservoir section.5

As a result of the setup of the project organization, it was evident for the service provider's single source of contact that the solution with the competing system was best for the well. Therefore, the service provider did not have a conflict for using this new option.

During the campaign, a decision was made to use a special contract between Det norske and a different service provider for finalizing well abandonment. This involved the use of a separate vessel for cutting the casings just below the surface and removing the wellhead. In this way, the rig left the well after all barriers for permanent abandonment were in place and after the installation of a trawl protection cap.

The specialized vessel removed the wellheads in a separate campaign, making the removal of wellheads a cost efficient operation without needing the rig. As a result of this separate contract, more rig time was allocated to drilling.

Technical performance

Benchmarking with other operations can verify the success of the drilling campaign. The campaign used Rushmore benchmarking for comparing efficiency trends with the rest of the industry in Norway. The comparison benchmarked the 10 Det norske wells drilled in the 16 well campaign with other exploration and appraisal wells drilled in the same period and area.

The comparison included only drilling of new wells between 2005 and 2010 on the Norwegian continental shelf by semisubmersible drilling rigs. It did not include any sidetracked well sections.

Figs. 5 and 6 show the benchmarking results. The left side of Fig. 5 shows that 6 of the 10 wells drilled in the campaign had a drilling rate equal to or better than the industry average. The right side of Fig. 5 shows that the drilling rate on average doubled throughout the drilling campaign.

Fig. 6 shows a similar comparison for drilling costs. It shows that 8 out of 10 wells had lower drilling costs than the cost for other operators, and 50% of the Det norske campaign wells have a lower cost than 75% of the comparable wells.

The right side of Fig. 6 shows that drilling costs fell during the drilling campaign. This cost reduction reflects the improved efficiency of the entire drilling operation.

Acknowledgments

The authors acknowledge Det norske oljeselskap ASA for providing the Rushmore benchmark data.

References

1. Landbo, O., et al., "Curing Shallow Water Flow in a North Sea Exploration Well Exposed to Shallow Gas," Paper No. SPE 124607, SPE Offshore Europe Oil & Gas Conference & Exhibition, Aberdeen, Sept. 8-11, 2009.

2. Landbo, O., et al., "Curing Shallow Water Flow in North Sea Exploration Wells," Paper No. SPE 124608, SPE/IADC Middle East Drilling Technology Conference & Exhibition, Manama, Bahrain, Oct. 26-28, 2009.

3. Jodestol, K., and Furuholt, E., "Will drill cuttings and drill mud harm cold water corals?," Paper No. SPE 126468. SPE International Conference on Health, Safety and Environment in Oil and Gas Exploration and Production, Rio de Janeiro, Apr. 12-14, 2010.

4. Saasen, A., et al., "Anchor Handling and Rig Move for Short Weather Windows During Exploration Drilling," Paper No. SPE 128442, SPE/IADC Drilling Conference and Exhibition, New Orleans, Feb. 2-4, 2010.

5. Saasen, A., et al., "Permanent Abandonment of a North Sea Well Using Unconsolidated Well Plugging Material," Paper No. SPE 133446, SPE Deepwater Drilling and Completions Conference, Galveston, Tex., Oct. 5-6, 2010.

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