Page 37: of Offshore Engineer Magazine (Apr/May 2014)

36 38

Geology & Geophysics has set out deliberately to explore this potential untapped resource, initially focusing on the West of

Shetland area, where the extremely old (2.33 – 3.2

Ba) and fractured Lewisian basement forms extensive ridges and localized highs, which are the focal point for charge from the prolifc Kimmeridge Clay source rock in the area.

However, other areas of the UKCS also offer base- ment potential, as now being promoted through the

PILOT (an industry/government group) New Plays

Initiative, as described in Sir Ian Wood’s February 2014 UKCS report Maximising Recovery Review (See page 25).

To date there is still no formal assessment from the government, geological survey, or oil industry on the resource potential of the UKCS Fractured base- ment play, however, Hurricane has made signifcant progress in evaluating the basement play West of

Shetland. A summary of that progress is provided below.

Progress in opening the UK’s basement play

Data acquired by Hurricane Energy through the drill- ing and drill stem testing of over a kilometre 1km of basement encountered in three wells has provided an insight into the reservoir properties of the Rona a new play for the UK

Ridge fractured basement Play. (See Fig. 2).

Analysis of these data has allowed for the detec- tion of productive fractures and characterization of

Basement potential in the UK fractured basement reservoir properties.

To date, basement on the UK Continental Fractured reservoirs require a different workfow

Shelf (UKCS) has largely been underexplored, to clastic reservoirs and basement is no exception. despite the fact that numerous indications of The workfow Hurricane has applied to exploring for hydrocarbons have been reported from base- hydrocarbon in basement West of Shetland is tried ment in wells dating back to the 1970s. As pro- and tested, and has successfully generated 450MM duction from the UKCS continues to decline, boe of 2C resources. The approach used includes: • and with the exploration potential of the more Prospect generation through the integration of traditional plays becoming increasingly mature, feldwork, seismic and well data • the potential from the overlooked and under- Successful well placement, targeting faults as rated basement play therefore warrants further defned on 3D seismic, with well prognosis of top exploration. basement and fault locations accurate to within

Over the past eight years Hurricane Energy meters

Thorough review of offset well data and global • analogues to establish optimum bottomhole assem- blies, resulting in rate of penetrations (ROPs) in the basement of 5-7m/hr and the acquisition of quality logging while drilling (LWD) data sets •

Generation of confdent static reservoir properties (e.g. fracture frequency, fracture orientation, and fracture porosity) from a combination of wireline and LWD data

Establishing an understanding of effective frac- • ture porosity, by comparing bulk porosity estimated through nuclear magnetic resonance and density neutron techniques, with discrete fracture porosity estimated from acoustic and electrical image logs.

Identifying dynamic reservoir properties from gross • fow zones, to fow rates estimated from single frac- tures, evaluated through image log and production

Fig3: Interval of borehole exhibiting preferential oil fow associated with a seismically mapped fault.

oedigital.com April 2014 | OE 39 000_OE0414_G&G-1_trice.indd 39 3/23/14 12:05 AM