Modelling Unconventional Wells with Resolve and Reveal Juan Biörklund (Gauloise Energía) and Georg Ziegler (Wintershall Holding)

Reveal Features Adsorption PVT Modelling Diffusion Reservoir Modelling Designed to study specialized near well bore effects and assess their impact on the production from the reservoir Adsorption Diffusion Rock Mechanics Rock Failure Fracturing PVT Modelling Reservoir Modelling Well Modelling Chemical EOR Water Chemistry

Capabilities (Resolve & Reveal) Quick Calculations Tight reservoirs with complex well geometries Systems with up to 20,000 wells with 100 wells being drilled per month Shale Oil / Gas Wells Horizontal, inclined and fractured wells Gas adsorption, diffusion, directional stress dependent permeability variations etc...

Concept Dimensionless transient reservoir response capturing the well, fracture and reservoir geometry Dimensionless pseudo-pressure pseudo-time (pD tD) Match this response to production history Modify reference parameters k and phi(rw2) Adjust PVT reference conditions for pD and tD

Concept (cont.) Perform predictions Use matched pD tD and super-position to predict Pwf Transient IPR for rate estimation Well scheduling Automate the procedures using visual workflows Model definition and workflow in Resolve Indirectly access simulation capabilities of Reveal

Shale Gas Well

Microseismic Frac Xf is 3 -5 x longer than seen in FracPro, proved with Microseismic Multi-Fracs does not interfear near wells (approx. 300m) (Sketch not same as seen)

Fracture Input Parameters

Fracture Finite Element Grid

History Match History match a shale well - Additional Input Data - Young’s modulus (248000 bar). Poisson’s ratio (0.275). Biot’s coefficient (0.75). Langmuir adsorption curve (70 scc/g). Fracture permeability variation (no data). Compaction table (Palmer & Mansoori – SPE 52607). Fracture geometry and properties (NRT Log & Gohfer)

History Match History matching : Reveal model

Input Parameters

History Match: Reveal Model Measured Pressure Calculated Pressure Rate

pD tD Curves - Resolve pD tD curves Why What they are A method that allows us to perform rapid calculations with complex well geometries What they are Dimensionless transient reservoir response that captures the well, fracture and reservoir geometry

pD tD Curves - Resolve pD tD curves (pseudo-pressure pseudo-time)

pD tD Curves - Resolve Optimization Resolve - Powerful Optimizing Tool on Field Level Production Why Resolve Handles large number of wells Easy to analyze well performance Infinite scenarios to find best match

pD tD Curves Use GAP with Eclipse / Reveal / pD tD pd td curve One well Reveal Model pd td curve Two well Eclipse

Resolve: Modelled vs. History

Shale Oil Well

Oil Models: Resolve & Reveal Issues No gas break-through seen in the simulation What is the frac geometry causing this behaviour? Tight Reservoir Module uses only analytical method (pD tD) 3 Fracs simulated as one, inflow problems Solutions Model the fracs explicitly with Reveal frac gridding option Evaluate resulting pD tD curves from analytical vs. numerical Detailed Resolve model explains where GOR increase when pressure is below Pb at certain fracs

Resolve pD tD Match Dimensionless parameters – no geometry info

Resolve Workflow

Control Reveal with Resolve Setup Resolve model and ran several cases to test sensitivity on different parameters and interaction between them such as: Porosity, Stimulated K, Matrix K Fracture half length, Fracture height Stimulated Rock Volume (SRV) Compressibility RESOLVE Logic

Resolve / Reveal Sensitivities

Oil Reservoir Model What is different between a Resolve analytical and a Reveal numerical model? Transfer fracture model from Resolve tight module to Reveal to back calculate geometry.

Reveal Oil Reservoir Model Model variable compaction table, stress dependent perm and changing cleat compressibility Pressure after one month

Effect of Cleat Compressibility 4.01 3.96 3.90 3.65 3.80 3.74 Effect of Cleat Compressibility Porosity Reduction with Pressure 27/11/2013 02/03/2014 30/06/2014

Changing Oil Density over Time 41.5 40.4 39.3 38.2 37.1 36.0 Reduction of Oil Density over Time 12/12/2013 31/01/2014 30/06/2014

Reservoir Model - Conclusions Porosity and compressibility have similar effects on BHP match Changes on SRV affects the late match Stress - Permeability function has an effect on the transient behaviour (early decline / build up) BHP calculation need careful considerations due to the instability of low rate wells. Stress dependent permeability needs to be included in the Reveal models to obtain a match

Thank you for your attention Questions?