Cross discipline use of the Modular Formation Dynamics Tester (MDT) in the North Sea

1. Cross discipline use of the Modular Formation Dynamics Tester (MDT) in the North Sea John Costaschuk, Dann Halverson, Andrew Robertson Res. Eng. Petrophysicist Geologist

2. Content • Defining the Value of Information and the Functionality of the Modular Formation Dynamics Tester (MDT) • Examples of value creation within BP’s North Sea operations: • Summary and Conclusions A. Operational Value • B. Subsurface Value • C. Project Value InSitu Fluid Analysis (IFA) IFA & Asphaltene EoS Vertical Interference Test Acquisition of live microbial samples

3. Defining the Value of Information • Many E&P decisions are difficult to make, involving significant capital expenditure for uncertain gain. • Value enhancement comes from allowing more robust decisions to be made, as a result of more reliable forecasting of the uncertain parameters and outcomes. • Operational • Subsurface • Project • Value of Information (VoI) compares the value associated with a decision, informed with and without extra information. • The reliability of the additional data is crucial to understand.

4. The Functionalityof the Modular Formation Dynamics Tester (MDT) Reservoir Formation Reservoir Formation • Conventional openhole pressure data is difficult to interpret in some areas of the resource: • Depletion signal impacts interpretation • Low matrix perm in parts of the reservoir • Adding IFA* data increases reliability of the fluid interpretation: • Viscosity • Optical Density • Fluid Density • Resistivity Sample Chambers InSitu Fluid Analyser High Pressure Pump Focused Sampling Probe Large Diameter Probe Guard Fluid Analyser for focused sampling * (IFA) InSitu Fluid Analyser

5. Operational Value of MDT • Operational Value of IFA: • Rapid determination of fluid contacts • Allows on the fly programme modification • Allows on the fly well test design modification • Resultant time cost saving on data acquisition. • Conversely allows you to optimise a programme when you only have a very limited time window. • Recent appraisal experience: • The top ranked objective of a well was to confirm OIP by establishing FWL within the segment • It was critical to ensure that a reliable free water sample was captured before weather terminated the operation. A. Operational Value • B. Subsurface Value • C. Project Value Insitu Fluid Analysis (IFA) IFA & asphaltene EoS Vertical Interference Test Acquisition of live microbial samples

6. Operational Value of MDTIFA confirmation that well objective met • What is the critical time estimate for clean-up, before which quality samples can be taken? Is the rock of adequate mobility? • Should the sample point be re-placed along the open-hole environment and clean-up restarted? • Under poor weather conditions, when have the objectives been met, and thus can the run be terminated?

7. Operational Value of MDTIFA confirmation that well objective met Shut-in Resistivity Shut-in Density

8. Operational Value of MDTIFA confirmation that well objective met Well Objective (#1) • Confirm OIP by establishing FWL within segment. IFA Observation • FLOWING: Resistivity saturated up to 6900s, but after this resistivity drops in spikes: non-continuous water phase (droplet) becomes more continuous; relatively low viscosity bulk phase • SHUT-IN: After the pumps are stopped at 10600s two immiscible fluids appear to segregate in the flowline, and a water density is measured at the AFA sensor at the bottom of the flowline IFA Interpretation • Mixed flow of two immiscible fluids when sampling • Free water phase • Oil phase or mud filtrate Reliable Information

9. Subsurface Value of MDTIFA integration with lab and depletion data Reliable Information • Subsurface Value of IFA and asphaltene EoS: • Alternate matches to the petroleum system model • Connectivity and compartmentalisation • B. Subsurface Value A. Operational Value • C. Project Value IFA & asphaltene EoS Vertical Interference Test Insitu Fluid Analysis (IFA) Acquisition of live microbial samples IFA Data Pressure Data

10. Subsurface Value of MDTVertical Interference Test Data • Subsurface Value of Vertical Interference Test data: • Uncalibrated petrophysical model • DST test / no test decision required • Kh and Kv/Khuncertainty in missing core interval • B. Subsurface Value A. Operational Value • C. Project Value IFA & asphaltene EoS Vertical Interference Test Insitu Fluid Analysis (IFA) Acquisition of live microbial samples

11. Project Value of MDTAcquisition of live microbial samples • Project Value in acquisition of live microbial samples • Reduce uncertainty on reservoir souring mechanism and evaluate injection water design options • Recent appraisal experience: • A specialised bottle preparation and sample handling protocol has been developed between BP, OilPlus and Schlumberger • Pressurised water samples are not required for molecular work • Pressurised water samples are required for transferring and setting up the culture • After three months incubation of the pressurised culture no significant hydrogen sulphide generation was observed (multiple bottles for each penetration). • B. Subsurface Value A. Operational Value • C. Project Value IFA & asphaltene EoS Vertical Interference Test Insitu Fluid Analysis (IFA) Acquisition of live microbial samples

12. Summary and Conclusions • Operational Value of InSitu Fluid Analyser (IFA): • When and where to sample relative to well objectives • Subsurface Value of IFA & asphaltene Equation of State: • Alternate matches to the petroleum system model • Connectivity and compartmentalisation • Subsurface Value of Vertical Interference Test data: • DST test / no test decision • Kh and Kv/Kh in missing core interval • Project Value of acquisition of live microbial samples

13. Questions • Thank you for your attention and interest. Credit: Paul Roylance & Gavin Fleming (Operations Geologists) Ilaria de Santo & Jonathan Haslanger (Schlumberger) Keith Robinson & Richard Jonson (Oil Plus)