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

Task 6 – Horizontal wells Review of progress since Dec 2000 meeting in Houston

Task 6 – Horizontal wells: Summary of decisions from December 2000 meeting n Pull together the experience from operators and modeling work done in the project to create –Operational best practices –Modeling best practices n Interest in the multifractured well injectivity correlation (Kuppe) for the Toolbox n Wrap up Task 6

New Work completed n Additions and revisions to the presentations at the Dec 2000 meeting: –“Analysis of Horizontal Well Injectivity - Example” –“Horizontal wells: Injectivity analysis – survey of tools and methods” n Best Practices for modeling Horizontal Wells – first draft completed n Work on the spreadsheet tool for multifractured wells in progress

Best Practices - Modeling n 4 main categories –Thermal effects on stresses –Thermal effects on PVT –Gridding issues –Fracture coupling n Examples of the magnitude of various effects n Examples drawn primarily from the Prudhoe Bay simulation work n Bibliography still incomplete

II prediction for multiply fractured well

Method - assumptions n Single phase, Darcy flow n Fully penetrating, infinite conductivity vertical fractures n Finite (closed) drainage area n II computed after Pseudo-steady state flow is reached n 1, 3, 5 and 7 fractures in a symmetric pattern

Method – correlation form n The injectivity index with fractures, II f, is calculated from the corresponding index for unfractured well II nf as: II f = Q/  P = II f = Q/  P = [( (2k H )(2X f h) C)/  B x) + II nf ] D [( (2k H )(2X f h) C)/  B x) + II nf ] D where C and D are complex coefficients: where C and D are complex coefficients:

Method – correlation form C = a 0 + a 1 k H + a 2 k H 2 + a 3 k H 3 C = a 0 + a 1 k H + a 2 k H 2 + a 3 k H 3 D =  +  X fd +  X fd 2 + X fd 3 D =  +  X fd +  X fd 2 + X fd 3 where X fd = X f /(L y /2) where X fd = X f /(L y /2) and coefficients depend on frac configuration and coefficients depend on frac configuration

Plan for completion of Task 6 n Operational best practices for horizontal wells –in cooperation with other contractors –Mainly extract operator’s experience n Peer review of Modeling best practices document n Incorporate the multifrac II tool in the PWRI Toolbox n Write “Best Practices” for horiz well injectivity calc using analytical techniques (to complement modeling) ?