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

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 ValueC. Project Value InSitu Fluid Analysis (IFA) IFA & Asphaltene EoS Vertical Interference Test Acquisition of live microbial samples

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.

The Functionality of the Modular Formation Dynamics Tester (MDT) 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 * (IFA) InSitu Fluid Analyser Sample Chambers InSitu Fluid Analyser High Pressure Pump Focused Sampling Probe Large Diameter Probe Guard Fluid Analyser for focused sampling

Operational Value of MDT B. Subsurface ValueC. Project Value Insitu Fluid Analysis (IFA) IFA & asphaltene EoS Vertical Interference Test Acquisition of live microbial samples A. Operational Value 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.

Operational Value of MDT IFA 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?

Operational Value of MDT IFA confirmation that well objective met Shut-in Resistivity Density

Operational Value of MDT IFA 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 8 Reliable Information

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

Subsurface Value of MDT Vertical Interference Test Data C. Project Value Insitu Fluid Analysis (IFA) Acquisition of live microbial samples A. Operational Value Subsurface Value of Vertical Interference Test data: −Uncalibrated petrophysical model −DST test / no test decision required −K h and K v /K h uncertainty in missing core interval B. Subsurface Value IFA & asphaltene EoS Vertical Interference Test

Project Value of MDT Acquisition of live microbial samples Insitu Fluid Analysis (IFA) C. Project Value Acquisition of live microbial samples A. Operational Value 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 IFA & asphaltene EoS Vertical Interference Test

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 −K h and K v /K h in missing core interval Project Value of acquisition of live microbial samples

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)