Objectives and Problems to be Solved:
Large amounts of unswept and bypassed hydrocarbon (oil and gas) deposits exist which can be extracted from existing wells if only we knew where to look for it. It is much cheaper and more environmentally friendly to identify and extract these from existing wells rather than drilling new ones. However, once a well has been drilled and casing has been set, conventional logging tools are unable to take measurements through the casing. The aim of this project is to optimise the recovery of hydrocarbons from existing wells by accurately locating oil and gas deposits behind casing, thus reducing the overall cost of production with minimal environmental impact. A neutron-logging tool is currently the only practical one for determining formation and fluid composition through casing. Improved interpretation of the neutron logging data which is obtained from cased-hole wells is needed in order optimise the recovery of hydrocarbons from these wells.
Description of Work:
Experience both in interpreting neutron logs and in trying to devise improved modelling techniques to aid in this interpretation have helped pinpoint the following two key areas that need to be addressed, and the way forward for each of them:
1. Data/Libraries: The current nuclear data libraries contain discrepancies and inconsistencies, and the library data format is often not immediately suitable for use with the modelling techniques available. These problems are addressed in an integrated way, within the framework of a new library supplement dedicated to borehole applications. It is aimed that this library supplement will grow to become an industry standard. Much can be done by reformatting and regrouping existing data, and the results of additional but incomplete measurements can be augmented using the latest modelling techniques.
2. Modelling: At present, radiation transport modelling (RTM) is too slow and not sufficiently accurate for well-logging applications. Techniques have been developed by the participants in this project proposal for both speeding up the traditional stochastic or Monte-Carlo approach to RTM, and in developing deterministic alternatives. These are adapted to treat nuclear borehole logging.
Expected Results and Exploitation Plans:
The five main deliverables are:
1. Launch of neutron data library supplement for borehole applications.
2. Algorithm for automated grouping of nuclear data into a format suitable for deterministic codes.
3. Extension of existing method to speed-up stochastic radiation transport in non-steady cases.
4. Wrap-up of 1-3 into user-friendly interpretation software package to locate oil behind casing.
5. Validation of the product 4 against experimental test-pit data and field-testing. The final package delivered in Item 4 will, after validation in Item 5, significantly enhance the effectiveness of our capability to manage mature fields. This may well lead to an additional 5% production from such fields within five years, at no additional environmental cost. In addition to end use of the product 4, exploitation of the results of the project will involve establishing 1 as an industry standard, thus positioning it for further development, and the exploration of commercial spin-offs of the improved radiation transport modelling capability developed during the project.
Funding SchemeCSC - Cost-sharing contracts
DT2 8ZE Dorchester
2629 JB Delft
SW7 2BP London
1755 ZG Petten