Norsk Hydro optimizes well paths with virtual reality technology

May 13, 2002
Norsk Hydro AS operates the Oseberg field in the Norwegian North Sea 130 km northwest of the company's headquarters in Bergen, Norway.

Norsk Hydro AS operates the Oseberg field in the Norwegian North Sea 130 km northwest of the company's headquarters in Bergen, Norway.

Virtual reality (VR) technology has allowed the company's field asset teams to optimize well and horizontal lateral placement within the reservoir, during both planning and drilling phases, of infill wells.

Drilled in 1999, Oseberg field B-29 well is a good example, with the well's VR designed horizontal completion encountering 65% oil-filled sand, compared to an average of 35% for nearby wells, according to the company.

Team members review a wellborn trajectory relative to reservoir features. Photo courtesy of Schlumberger.
Click here to enlarge image

Norsk Hydro in collaboration with Christian Michelsen Research AS of Bergen, Norway, developed the technology in the late 1990s, which they named Inside Reality.

The company decided to commercialize the effort in 1999, resulting in the spin-off of Inside Reality as a new company in 2000. Schlumberger Ltd's. Information Solutions acquired Inside Reality, based on the same technology under license from Norsk Hydro, earlier this year (OGJ, Feb. 18, 2002, p. 79).

Oseberg field

Norsk Hydro began production from the Oseberg field in 1988. Production is from the Brent group, which consists of the Oseberg, Rannoch, Etive, Ness, and Tarbert formations, where the Oseberg is the main reservoir unit.1

Due to a much lower recovery factor from the heterogeneous Ness formation than from the other formations, the Ness became the main target for infill drilling.1 Also, with the field going on production decline in 1998, the company initiated extensive infill drilling to extend field life.

A team member uses Inside Reality to position drilling targets. Photo courtesy of Schlumberger.
Click here to enlarge image

The Ness formation consists of a series of delta plain channel sandstones braided with coal beds.1 Sand lobes vary in width from 50 to 400 m and in thickness from 1.5 to 15 m.

With no accurate reservoir simulation model available for the Ness formation, Norsk Hydro has relied extensively on technology that enables a 3D view of the reservoir to optimize well paths in the Ness channels.1

The company drills and completes a typical Oseberg well with 10 3/4-in. casing from surface, which is tapered to 95/8-in. casing, cemented to the top of the reservoir. The rig drills an 8 1/2-in. horizontal lateral, then runs, cements, and perforates a 7-in. liner.1

B-29 well

The asset team rendered the targeted section of the Ness formation as a function of acoustic impedance, which corresponded to the oil-filled sands that the horizontal lateral was to intersect and connect.

The initially proposed B-29 well path, based on reservoir simulation, appeared as a straight line through the rendering of the reservoir block. Viewed with the VR system, it became clear that the straight path would not fulfill the objective of maximizing sand penetration.

The team designed a new well path interactively by placing target points directly inside the acoustic impedance bodies, resulting in a more complex well trajectory.

During drilling operations, according to the company, the latest drilling results were updated at least twice daily and the team arranged for well-status meetings.

On several occasions, the team engaged in active geosteering, in which they contacted the rig with new drilling instructions. With these operations confined to a short time frame, the VR system proved to be valuable for making difficult decisions quickly.

The Oseberg asset team attributed the VR technology with a major role in achieving the B-29 well results.

Virtual-reality technology

In 1996, Norsk Hydro had laid plans for a new VR research and development project that would allow asset teams to better position well paths and reduce well planning time, according to a press release.

The company joined in collaboration with Christian Michelsen Research AS of Bergen, Norway, which resulted in development of a VR software system for seismic interpretation, well planning, and reservoir modeling.

Norsk Hydro said that by 1998, the company had installed the system and began to use it regularly for well planning and geosteering well paths in the Oseberg field.

Demonstrated in February at the International Association of Drilling Contractors and Society of Petroleum Engineers 2002 Drilling Conference, Dallas, the VR system immersed viewers in the reservoir with a large screen and stereoscopic display.

Wired head and hand sets eliminated the need for a keyboard and mouse, which gave the VR system a 3D user interface that allowed users to manipulate reservoir images with intuitive gestures like walking, pointing, grabbing, and drawing.

Bending at the knees, the reservoir block appeared to tilt upwards, revealing the underneath view of the formation and wellbore trajectories. Standing straight gave a fly-over view, looking down at the reservoir's top as wellbores descended from an imaginary surface that was somewhere overhead.

A click and motion with the hand-held device allowed the user to isolate and zoom-in on a portion of the reservoir that may have had complicated geometry or to get a closer look at a region that caught the attention.

When attempting to design the path of a hypothetical well, the system gave an alarm or indication when a selected wellbore target was significantly out of the well's trajectory and would have resulted in a dog-leg severity that was beyond the preset limits.

Reference

  1. Rundgren, G., Algeroy, J., Hestenes, L.E., Jokela, T., and Raw, I., "Installation of Advanced Completions in the Oseberg 30/9-B-38 B Well," SPE paper 71677, presented at SPE Annual Technical Conference and Exhibition, New Orleans, Sept. 30-Oct. 3, 2001.