Produced Water Reinjection Performance Joint Industry Project TerraTek, Inc. Triangle Engineering Taurus Reservoir Solutions (DE&S) E-first Technologies Advantek

Data analysis –Data sets analyzed previously: –Elf 3 Well 1 + 2, Statoil Heidrun, Marathon W. Brae –Additional data sets: –Phillips T field –KMG G field –Simple damage model applied to Elf 3 –Each dataset has unique interpretation problems –Analysis of impairment of injectivity (k, S)

Methodology for analysis 1. Convert THP to BHP 2. Find and mark all significant events (stimulations, transition matrix-frac,…) 3. Conventional p,Q vs t and p vs Q plots 4. Modified Hall plot (consider variations in p res ) 5. Check initial (or expected) injectivity by analytical or numerical calculation

Methodology for analysis – cont’d 6. If fracturing identified, check frac pressure from all available sources 7. Calculate II in matrix mode 8. Calculate II in fracture mode 9. If good data is obtained for number of datasets, correlate II changes with basic parameters 10. Try to develop general correlation (similar to PEA23)

Phillips T field characteristics  Fractured chalk reservoir, production wells have negative skins  Raw data processed through the BHP spreadsheet tool - validation  Reservoir pressure increased with time from 2125 to 3000 psia (92-96). Pres vs t for analysis was taken from reservoir simulator output  SW injection only (additional info -acid washes)

Phillips T field chalk Well 1

Phillips T field Well 1 – reservoir pressure

Phillips T field chalk Well 2

Phillips T field Well 2 – reservoir pressure

KMG G field  3-10 D, 32 % porosity, 2 wells (W4 and W4A)  Mixture of PW and aquifer water from the start  OH+ gravelpack (W4) or excluder (W4A)  No fracturing? (no data on frac gradient either)  Almost exact analog to Harding (SPE ….UK DOE)  Assumed high completion skin:  S=100 for gravelpack (W4)  S=250 for excluder screen (W4A)

KMG G field well W4

KMG G field W4 – injectivity decline

KMG G field well W4A

KMG G field well W4A – injectivity decline

KMG G field – injectivity comparison with BP field D

Summary

Conclusions n All data sets show significant reduction of injectivity compared to theoretical n Perm reduction and skin plots help visualize the problem n Completion skin included as a separate item now n Each case must be processed very carefully, assembly line approach will give misleading results n Simple damage model looks promising, can incorporate dynamic changes (p(t), stimulations, …)