How Geosciences Integration Led to the Re-Birth of an Old Discovery: Hild East, Norway

Mathieu, Christian H.¹; Hope, Rune R.³; Bruckert, Louis ²; Kvinnsland, Steinar ³
(1) DGEP/GSR/CAE/EN-ECA, TOTAL, PARIS La Défense, France. (2) DGEP/GSR/VDG, TOTAL, Paris La Défense, France. (3) GSR, TOTAL E&P NORWAY, Stavanger, Norway.

Up to now all the papers speaking about Hild focused on seismic imaging. Indeed one of the most recent publication (Hild multi azimuth seismic experiment, K. Kravik, 2005) delt with a so called experiment! This is why it is a pleasure to show how TOTAL EP Norway made a giant step from a seismic experiment to the filing of a dedicated Field Development plan (FDP) through the integration of various Geosciences techniques.

After a review of the main difficulties which impaired the delay between the discovery and the decision to launch a development, the latest seismic imaging progress and their impact on the interpretation as well as the Hild East penetrations drilled in 2009-2010 and the Extended Well Test (EWT) results will be summarized.

Integration of these various Geosciences techniques led to a much better understanding of the Hild East discovery. This will allow TOTAL E&P Norway to file a FDP before August 2012 and to operate again a major 150-250 Mboe field in the Norwegian waters.

The current Hild field project (TOTAL operator 49%, Statoil 21%, Petoro 30%) includes the development of the Hild East gas reservoir and the smaller over laying Frigg oil reservoir, located in 115m water depth, which are straddling blocks 30/4a and 30/7a along the borderline between UK and Norway in the Norwegian sector. The Hild East discovery was made by Norsk Hydro in 1978 by the well 30/7-6R and was followed, between 1979 and 1984, by 4 other gas discoveries in the Brent Group with pressure ranging between 750 and 800 bars and different gas gradients. On top of these facts, seismic imaging was a major challenge because the presence of a gas dismigration in the over laying Cretaceous series created a seismic obscured area over 30Km². Given the poor seismic image and the apparent heterogeneity in the pressure measurements, particularly in wells 30/7-6R and 30/4-2, it was admitted that the Hild East discovery was highly compartmentalized and, as a consequence, that an economic development would be out of reach.

In 2005 a High Density Wide Azimuth 4C OBC was acquired providing a step improvement in imaging/illumination of the deep objectives. This allowed drilling a pilot hole plus a deviated well straddling two undrilled segments. Then a EWT consisting in producing and flaring the Brent gas during 10 days and monitoring the pressure build up was carried out: it demonstrated a significant reduction of the segmentation risk.

AAPG Search and Discovery Article #90135©2011 AAPG International Conference and Exhibition, Milan, Italy, 23-26 October 2011.