Sponsors

BP Exploration Ltd
DTI, Oil & Gas Division
Elf Exploration plc
Enterprise Oil plc
Marathon Oil (UK) Ltd
Mobil North Sea Ltd
Shell UK E&P
Total Oil Marine plc

Research Providers:

AEA Technology
Heriot-Watt University
Imperial College of Science, Technology & Medicine

Project Monitoring:

PSTI
under assignment from DTI Oil & Gas Division

Project Cost:

£1,300,000

Participation:

Industry: £150,000 over 3 years

DTI: £200,000 over 3 years

The Requiremements

Screening studies have suggested that reservoir depressurisation at a late stage of waterflooding could be an economic option for some ten reservoirs on the UKCS. The DTI estimates the overall potential for increasing hydrocarbon recovery could be as high as 800 million STB of oil equivalent at current oil prices.

Whilst a considerable amount of research has been performed to study natural depletion and solution gas release in virgin reservoirs, depressurisation of waterflooded reservoirs has received comparatively little attention in the literature. There is a shortage of quantitative data needed to evaluate applications and there is insufficient understanding of the process to allow existing data to be extrapolated or interpolated for general use. For this reason, a multi-client club funded project has been initiated to focus UK expertise in IOR research towards the requirements for depressurisation applications on the UKCS.

The Objectives

The primary objectives of the research programme are:-

to provide reservoir condition data and calculation procedures which can be used to evaluate UKCS depressurisation field applications;

to undertake a number of reservoir conditions depressurisation experiments using core materials and fluids taken from UKCS reservoirs;

to evaluate the effectiveness of existing reservoir simulators for predicting the performance of depressurisation field projects.

Synopsis

The purpose of the research is to further the state of knowledge on depessurisation, so that future field projects can be evaluated and designed with increased confidence. It includes depressurisation experiments using resrevoir cores and fluids, to produce additional data at reservoir conditions, with particular emphasis being given to measurements at the low pressure decline rates to be expected in practice. To enable this data to be translated to other reservoir situations, the programme is also designed to provide information which will create an understanding of the physical phenomena occurring under these conditions, and to use this information in developing models of the proccess for inclusion in reservoir simulators.

Deliverables

Simulation studies to identify:
(a) the reservoir characteristics and fluid flow parameters that most influence the viability of depressurisation field projects; and
(b) future requirements for simulator development.

High pressure core experiments which will produce additional data at reservoir conditions.

Experimental and theoretical studies designed to create an understanding of the processes involved so that experimental data can be translated to other reservoir situations.

About the Research Providers

AEA Technology:- Has specific experience in development and use of reservoir simulators and in the performance of reservoir condition core experiments, having already undertaken a number of high pressure depressurisation experiments related to gas condensate reservoirs. The depressurisation programme will use this expertise for the reservoir related studies.

Heriot-Watt University, Dept of Petroleum Engineering:- Highly rated reputation for its abilities to perform integrated theoretical and experimental research programmes directed towards fundamental and practical aspects of various reservoir processes. Expertise will be brought to the programme for the high pressure micromodel experiments and for network modelling.

Imperial College, Reservoir Physics Group:- Has a long history of respected research expertise in reservoir physics. This expertise will be incorporatedinto the programme by performing a research programme at low pressure following the Group's successful use of low pressure micromodels to study the physics at pore scale, and to observe behaviour directly in two and three phase displacement processes.

Note:- The project is a synthesis of three complementary proposals submitted for funding to the DTI's ACEORR (Improved Oil Recovery) research support scheme in 1993. Following a DTI initiative to merge these projects, contractual project management was assigned to PSTI.