Cross discipline use of the Modular Formation Dynamics

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: A. Operational Value B. Subsurface Value In. Situ Fluid IFA & Asphaltene Eo. S Analysis Vertical Interference Test (IFA) • Summary and Conclusions C. Project Value 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 (Vo. I) 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) 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 High Pressure Pump Focused Sampling Probe * (IFA) In. Situ Fluid Analyser Large Diameter Probe Guard Fluid Analyser focused sampling Reservoir Formation In. Situ Fluid Analyser Reservoir Formation Adding IFA* data increases reliability of the fluid interpretation: • Viscosity • Optical Density • Fluid Density • Resistivity Sample Chambers

Operational Value of MDT Operational Value of IFA: A. Operational Value • • Rapid determination of fluid contacts Allows on the fly programme modification B. Subsurface C. modification Project Value Allows on the fly. Value well test design 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: Insitu Fluid Analysis (IFA) • IFA The&top ranked objective of a well was to confirm OIP asphaltene Eo. S Acquisition of live by establishing FWL within the segment microbial samples Test that a reliable • Vertical It was. Interference critical to ensure 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 Shut-in 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 6900 s, 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 10600 s 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 8

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

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

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

Summary and Conclusions • Operational Value of In. Situ 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

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)