?The reservoir evaluation tool connects to the surface by unspooling an interior electrical cable that powers the electrical motors and continuously transfers data back to the surface.

?Will future exploration and appraisal wells be drilled without a rig?


There may be a new way of determining the extent of an offshore asset without using a rig. Sigmund Stokka, research director for the International Research Institute of Stavanger (IRIS), developed the concept of the Badger Explorer in 1999. The device was patented in 2002 in Norway and 2005 in the U.S.


Procom Venture was responsible for the initial launch of Badger Explorer ASA, and, in 2005, the company entered into contracts for funding and cooperation with ExxonMobil Corp., Royal Dutch Shell, StatoilHydro ASA, and the Research Council of Norway to develop a prototype for the tool.


The device recently passed its first test onshore Denmark, and is on its way to becoming a low-cost, low-risk method of evaluating reservoirs. Badger Explorer is designed with a full package of logging sensors that characterize downhole environments once the tool drills into the ground and buries itself.


It penetrates the seabed using a mechanical drillbit driven by an electrical motor. As the bit loosens and crushes the formation ahead, it transports the matter through the device, thus depositing the remains in the void behind the tool. The excess volume is forced and injected into the formation through fractures generated by the tool.


The tool connects to the surface by unspooling an interior electrical cable that powers the electrical motors and provides continuous transfer of data back to the surface. The system drills underground without the risks, cost or complexity of exploration drilling with a rig. It’s been labeled a “rigless,” autonomous “fly-by-wire” exploration tool.


The current prototype version is non-reusable and remains underground. It can penetrate the subsea surface to a depth of 9,843 feet in about two months with an average rate of penetration of 6.5 feet per hour, depending on rock hardness. The tool generates a six-inch borehole and runs on 10 kilowatts of power while recording and logging all traditional parameters of a well.


The device drills formations in gauge hole, with no drilling fluid and without overbalance, which guards against formation invasion and measurement errors due to washed-out hole sections. As a result, the measurements of formation properties are simplified, requiring simpler tool strings compared with what is necessary for conventional drilling.


This reduces costs related to the measurement sensor package in the tool and increases the quality of the data. Because it is hardwired to the surface, the data-sampling rate and transmission volume for measurement and logging while drilling are much higher than traditional methods.


The new device has positive implications for the environment, including a reduced impact on wildlife, fisheries and the surrounding area. The method doesn’t require large drilling rigs or related logistics, so it also cuts down on emissions to air or sea. The self-contained process requires no vessel assistance, so it could also reduce hazards for personnel and reduce fuel consumption during operations.


Beginning in 2005, the Badger Explorer Prototype Development Project leaders’ goal was to finalize a detail design, build a full-scale prototype, perform a full-scale test and execute a pilot installation within two to five years.


Badger Explorer ASA recently completed the first part of its Demo50 full-scale prototype test at the Denmark site. “The achievements verify the design and the capabilities of the technology at this stage,” says the company’s chief executive, Kjell Erik Drevdal.


The first round of Demo50 tests focused on several functions, including drilling and pumping, cuttings and fluid transportation. The test also provided the researchers with operational experience from the site, a chance to associate with service and equipment suppliers in the area and ideas on how to improve techniques in separating cuttings and fluid.


At press time, the company was assembling the semi-autonomous drilling unit to undergo a subterranean, self-burying drilling test at the same site.


If successful, the new device could reduce the cost of exploration in some areas by up to 80%, thus increasing the number of discoveries within a set exploration budget. It could also reduce the initial investment for each find, which could increase the value of proven and recoverable reserves and allow better long-term planning.


Joint-venture partners ExxonMobil, Shell and StatoilHydro have already secured first rights of refusal to buy the full manufacturing and operational capacity of the new device for a three-year period from commercialization, which is expected in 2010.

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