6. Improvements in satellite-derived gravity data lead to more efficient hydrocarbon exploration
Submitting InstitutionUniversity of Leeds
Unit of AssessmentEarth Systems and Environmental Sciences
Summary Impact TypeTechnological
Research Subject Area(s)
Engineering: Geomatic Engineering
Summary of the impact
Research carried out at the University of Leeds has been used to develop
data sets that are now routinely used in offshore oil exploration to
identify prospective areas faster, and with reduced cost. New techniques
applied to satellite altimeter data have been used to compute gravity
anomalies in marine areas with increased accuracy and reliability relative
to earlier products. These anomalies have been developed during the REF
period in association with a University of Leeds spin-out company (Getech)
into a global data set, which has been sold and licensed extensively
within the hydrocarbon exploration industry. The global data set has
delivered economic and reputational benefits to Getech, and has been
employed by oil companies in more than 50 exploration projects per year.
Shell values the improved gravity data at $2.5M per project.
By the mid-1990s, the use of marine gravity data sets derived from
satellite altimeter data had become well established for offshore
hydrocarbon exploration, as well as for general geological studies and for
the development of global geoid and gravity models. However, although
satellite altimeter data with good coverage were available (~4 km track
spacing over most of the oceans), the resolution of the derived gravity
grids was significantly worse, particularly in coastal regions. In
consequence, the potential applications of satellite gravity anomalies
were limited in scope by the available data.
Between 1996 and 1998, Leeds researchers Derek Fairhead, Chris Green,
and Stefan Maus (Researcher, 1996-1998) developed an improved method of
detecting marine gravity anomalies using satellite altimeter data. Their
approach was to use the most basic altimeter data available - the raw
waveforms transmitted from and recorded by the satellite. This relatively
large data set required sophisticated processing, and a range of new
techniques were developed to pick the exact return time of the radar
echoes, and to test the robustness and accuracy of the retrievals. The
results demonstrated a significant improvement over previously-available
along-track data, enabling the production of improved gravity anomaly
Subsequent research (1997-1998) by Green and Fairhead in
association with Getech reviewed the whole process of generating satellite
gravity data. By modifying the details of the various techniques, it was
shown that the improved along-track satellite altimeter data could be
processed to provide improved gravity anomaly grids. Paper  and
report  describe these techniques and demonstrate that the
improvement in results compared with gravity data from other sources is
better than 10% (see also corroboration [B, C]). These new
techniques were later (2002-2004) applied by Getech to develop a new
gravity data set for the continental margins of the world .
Paper  looks at a specific area of interest and quantifies the
improvement achieved by applying the new techniques.
Sustained collaboration between Getech and the University of Leeds has
driven further advances in the technology. In 2008, Fairhead led
research on the effectiveness of combining gravity data sets derived from
different satellite missions, resulting in the production of Getech's new
Trident marine gravity product with improved resolution and
reliability . In 2012, Green and Fairhead
initiated a joint research collaboration with Leeds to maintain their
industry-leading position by incorporating the latest generation of
interferometric satellite altimeter data. This project has now evolved
into a major 3-year oil industry sponsored study (2013-2016) to improve,
yet further, the resolution of the data.
The impact of the research has been achieved via Getech, primarily
through the sale of gravity data products, which are used by oil companies
in hydrocarbon exploration.
Derek Fairhead, Lecturer and Professor (now Emeritus)
(1973-present) of Applied Geophysics in the School of Earth and
Environment, University of Leeds; Managing Director (1991-2011) and
President (2011-present) of Getech
Chris Green, Research Assistant (1983-1992) and Teaching Assistant
(2010-present) in the School of Earth and Environment, University of
Leeds; Scientist (1992-2010) at Getech
References to the research
This list includes both academic references and commercial reports as
both are important in the disemination of the research.
1. Maus, S., Green, C.M. and Fairhead, J.D. (1998).
Improved ocean-geoid resolution from retracked ERS-1 satellite altimeter
waveforms. Geophysical Journal International, 134,
Paper describing the research that led to the impact.
2. Fairhead, J.D., Green, C.M. and Odegard, M.E. (2001).
Satellite-derived gravity having an impact on marine exploration. The
Leading Edge, 20, 873-876. doi:10.1190/1.1487298.
3. Bansal, A.R., Fairhead, J.D., Green, C.M. and
Fletcher, K.M.U. (2005). Revised gravity for offshore India and the
isostatic compensation of submarine features. Tectonophysics, 404,
1- 22. doi:10.1016/j.tecto.2005.03.017.
4. Fairhead, J.D., Williams, S.E., Fletcher, K.M.U, Green,
C.M and Vincent, K. (2009). Trident — A New Satellite Gravity Model
for the Oceans. Extended Abstract, 71st EAGE Conference
and Exhibition, Amsterdam.
5. Towards the Ultimate Resolution of Satellite Gravity.
Confidential Getech report G9815. May 1998.
Commercially funded R&D project.
6. Global Continental Margins Gravity Study (GCMGS). Confidential
Getech report G0411. June 2004.
Industry funded R&D and processing project leading to a
near-global gravity grid.
The research described in ,  and  is of
international significance as approaches similar to those described have
been used in recent satellite gravity data sets produced in both Europe
and North America. The work reported in  is the best
publically-available description of the Trident development. Commercial
reports , , and  have led to significant
sponsorship of follow-on studies and sales of the products developed.
Details of the impact
The impact of the research has been to aid the effectiveness and
efficiency of global oil exploration, especially in frontier continental
margin areas. Oil companies have used the improved satellite gravity data
sets [4, 6] to perform many rapid, low cost geological evaluations
of marine areas.
The construction of the GCMGS data set (2004) was initially sponsored by
ENI, Shell, Statoil and Total, but the reach has been subsequently
extended by Getech licensing the product in part or in full to most of the
world's leading oil companies. A further enhanced product, the Trident
data set, released in 2008 has maintained the reach and market leadership.
Letters from the initial sponsors [A1, A2], [B], [C],
[D] attest to the widespread use of the derived data sets, whilst
the added value of the Trident data set is noted in letters [A1, A2],
[C] and [D].
Exploring for hydrocarbons offshore is an expensive and risky business
and hence oil companies use a variety of data sets in the process (see [A1]).
Gravity data can be used as a tool to map and model target geological
structures beneath the seabed. Access to spatial data sets, such as
satellite gravity, can have a massive impact on targeting potential oil
structures which can be followed up by more detailed and expensive
exploration methods such as 3D seismic and CSEM prior to drilling.
Satellite-derived gravity data sets were available in the mid-1990s.
However, take-up of these early products as a commercial exploration tool
was modest due to their limited accuracy, resolution and reliability. The
improvements in resolution that were made through this research led to a
step change in the use of satellite altimeter data to grade frontier
offshore areas for exploration. Satellite gravity data are now widely used
throughout the offshore oil industry, and Getech is a major supplier.
Although gravity data measured on a ship or on the seabed can provide
better accuracy and resolution than satellite gravity, they are relatively
expensive and time consuming to acquire - and speed is a major factor in
exploration as it is competitive and often needs to be carried out to
specific timetables. Satellite data, on the other hand, are valuable,
because they are already available for any offshore area and enable rapid
assessment of new exploration areas. In consequence, satellite gravity
data continue to be used by oil and gas companies for hydrocarbon
exploration — especially in frontier areas or at regional scales (see [A1]).
The economic value of the underpinning research can be measured in terms
of the value of the Getech marine gravity data to their customers; this is
related to the value of the data for each offshore exploration and the
number of times the data have been employed. According to Shell [A1],
cost savings afforded by the use of satellite marine gravity data are
related to the improvement in quality (accuracy, resolution and
reliability) over alternative products, and they estimate that a 10%
improvement in the reliability of marine gravity data yields at least
US$2.5M increase in the value of a single project. Two other Getech
customers confirm that the use of Getech Trident data set has indeed led
to a 10% improvement in the reliability of marine gravity data for
prospecting [B, C]. Four Getech customers [A1, A2, B, C,
and D] confirm that the Getech marine gravity data have been used
routinely for frontier exploration in offshore areas, and three of these
customers [A2, B, C] state that the Trident data set has been used
in 3, 35-40, and 12 exploration projects per year, respectively.
In addition to reducing commercial risk, the increased use of satellite
data has the added advantage of mitigating other risks associated with
exploration (see [A1]). Limiting risks to personnel and the
environment is very important to exploration companies; thus, technologies
which do not involve people working on the ground have important
The underpinning research has of course also been of economic value to
Getech itself [E]; the improved gravity anomaly data have
benefited the company through income and through reputational gain. Getech
received £1.2M between 2002 and 2004 from six leading oil companies for
their initial marine gravity data set, helping enable the company to be
floated in 2005. Since then, and during the REF period, Getech has
licensed updated versions of the gravity data sets to sponsors, developed
as a consequence of technological improvements derived from the
underpinning research. The long-standing collaboration between Getech and
the University of Leeds has therefore maintained the economic impact and
reach of the underpinning research.
Sources to corroborate the impact
A1. Letter from senior scientist at Shell (dated 8/11/2011). This
provides an indication of the impact of the results of the research on the
hydrocarbon exploration process. This letter is particularly helpful, as
it aids in quantifying the commercial impact of the work. Available on
A2. Letter from senior scientist at Shell (dated 21/11/2013)
clarifying the number of exploration studies in which the data have been
used. Available on request.
B. Letter from ENI (dated 21/11/2013). This indicates that the
data set derived from the research is in regular use for oil exploration
by ENI and is considered to represent an improvement on previously
available data sets. Available on request.
C. Letter from Statoil (received 21/11/2013). This provides
evidence that the data set based on the research has been extensively used
in Statoil's exploration process; it indicates how the new data are better
and their perceived importance to Statoil. Available on request.
D. Letter re. Total (received 3/11/2011). This letter was written
by a former Total employee who headed up Total's involvement in the
satellite derived data products. It confirms that the data sets have been
routinely used by Total and that the Trident data set has further improved
the product. Available on request.
E. Letter from Getech (dated 21/11/2013). This letter written by
the Chief Executive Officer describes the economic and reputational impact
of the underpinning research for the spin out company.