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

Data Analysis –Data sets analyzed: Elf 3 Well Statoil Heidrun B3H Marathon West Brae –Each dataset has unique interpretation problems –Analysis of impairment of injectivity (k, S) –Simple damage model

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)

Elf 3 Characteristics  PW only, high solids content, extreme plugging  Frequent acid jobs  Difficulty in deciding matrix vs fracture regime due to imposed THP limitation of 90 bars  Analysis shows extreme reduction in perm (or skins on the order of 1000)

Statoil Heidrun B3H  Fracture and matrix injection, SW only  Difficulties with BHP conversion and p res interpretation  Significant damage (k/10, S=100)

Marathon West Brae  SW only, very detailed history  Hall plot shows unexplained slope change (after shutdown?)  Large damage (k/100, S=800)

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 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, …)