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Rigless drilling enters the pilot stage

Written by  Victor Schmidt Monday, 01 April 2013 00:00

Exploration could be radically altered by a simple idea, Victor Schmidt explains, saving industry months and millions.

How does the offshore industry evaluate a new deepwater play? Conduct geologic research, examine studies, collect samples, acquire seismic, process, interpret, budget, and ultimately contract a rig to drill a hole. It’s a time-consuming and expensive process, especially the sample/seismic/drilling segments.

The Badger tool is guided into position by an ROV, which then connects it by cable to a subsea power source.

What if there were a way to quickly and inexpensively (relatively speaking) gather the needed information to test a play idea, or quickly evaluate a traditionally discovered deepwater reservoir ahead of full field development. Think of the money it could save and the increased number of play ideas that could be tested. The industry has done this before by drilling small diameter expendable holes, but this approach is only practical for shallow-depth targets.

That idea, quick evaluation, is the driver behind the Badger Explorer tool concept now under development by Stavangar-based Badger Explorer ASA. The concept is deceptively simple: lower an expendable tool to the seabed to drill through rock formations, and evaluate the rocks as the tool moves downward through the earth’s layers. When the target depth is reached, abandon the tool. Just clip the cord and walk away; the tool is permanently sealed in the rock. If the tool is used for field evaluation, it can remain active as a sensor set for the life of the tool, once the field is developed.

According to Badger, it will work like this:

The tool will be lowered to the seabed from a vessel of opportunity and be connected to a power source, using an ROV if in a developing field. The electrically-powered drilling system will then start burrowing into the subsurface. As the tool moves into the earth, formation fluid will circulate from the outer annulus down to the bit, carrying cuttings to the top of the tool, where they will be compacted above the tool filling the hole as the tool advances.

While drilling, the tool’s sensors will record data continuously and send it uphole by a power and communication cable that will pay out behind the advancing tool. The MWD logs produced from the data stream will allow formation evaluation in real-time and yield data to fine-tune both geologic models and seismic datasets. In field surveillance mode, the sensors will produce continuous, long-term data for production monitoring.

Fluid transfers drill cuttings up the tool’s center to a compacting element at the top. This fills the void space, as a spooled power/ communications cable pays out from inside the tool.

Goals for the tool include drilling a 6in. hole to 3000m TVD in two months (average rate of penetration of 2m/h). Traditional logging parameters (gamma ray, acoustic response, pressure, temperature, resistivity, neutron porosity, fluids testing, etc.) will be recorded. Power required is gauged at 10 kW.

Research program

Badger Explorer was created in 2003 to carry this idea forward. The Research Council of Norway (RCN) and three sponsors: ExxonMobil, Shell and Statoil supported basic research behind the idea.

During 2012 significant progress was made. A structured evaluation of the tool design was conducted, to identify and evaluate elements that could limit longer-term capabilities. Challenges considered included subsea operations, deeper drilling, rock formation types, and drilling through gas zones.

A beta version of the tool was produced and work continued on the cable storage system. An improved drilling unit was designed and the test jig modified. Tests included: drill bit, stone crusher, and the transport system.

The compaction system was improved and the need for clean circulation water while crossing gas zones was eliminated. A way to quantify apparent compaction was devised and is being tested. Flow capabilities of drilled cuttings with low fluid content were also tested.

The number of tool segments was increased and a low-friction coating was chosen for the tool body. In addition, a commercial frameless motor was selected to drive the bit.

New Resources

After the basic research phase, Badger moved into Phase 2 – Pre- commercial and its Demonstrator Program (DP). Exxon and Statoil carried over into this phase and Chevron replaced Shell as a supporter. The company received a boost recently when it added a fourth sponsor, Wintershall, to the DP.

The DP establishes a design basis for the next generation Badger tool, where lessons from the prototype will be used to develop and configure the tool for commercial applications. This involves choosing sensors and instrumentation for use during the drilling process, as well as sensors for long-term reservoir monitoring and management.

According to the company’s 4Q 2012 Quarterly Report, the addition of new sponsors fulfills conditions for additional funding from Innovation Norway. The first part of a grant of NOK20 million will be given to Badger to support the DP, with remaining payments based on other milestones during 2013 and 2014.

This phase is slated for three years. The company plans to deliver the tool for its first field pilot tests after completing the DP later this year. These pilots will be undertaken as a separate program, to which the Research Council of Norway has already awarded NOK8 million of support.

The first field pilot is slated for the Canadian oil sands, even though some qualification and permits are required. Other sites, some in Norway, were investigated to avoid any delay in the technical program.

The first pilot tool will face the challenge of glacial tills, mudstones and relatively unconsolidated formations, conditions similar to many locations across the globe. A second pilot will test geology representative of the Barents Sea.

Badger Explorer expects to introduce the tool to the commercial market sometime in 2015. OE

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