Case Study One

Case Study 1: Nechelik Field — Multi-Well Pressure Interference & Drainage Simulation
A fully implicit 2D finite-difference reservoir simulator built in MATLAB to model transient pressure evolution and multi-well interference in a heterogeneous clastic reservoir, using real-field geostatistical data.
 
 
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Client & context
Developed internally at GSERC as a pedagogical and decision-support tool for African independent operators and university trainees. The project addresses the need for accessible, validated reservoir simulation without the cost barrier of commercial software licenses.
Problem statement
African operators and trainees need access to reservoir simulation tools that can:
• Model heterogeneous reservoirs with real geostatistical data
• Capture multi-well interference and drainage efficiency
• Validate numerical results against analytical benchmarks
• Run without expensive commercial licenses (ECLIPSE, INTERSECT, CMG)
Methodology
 

Step 1 — Grid construction. Built a 54 × 22 finite-difference grid (1,188 active blocks) over a reservoir footprint of 7,060 ft × 5,753 ft × 100 ft. Imported spatially varying porosity and permeability from Nechelik field datasets. Inactive cells (NaN / zero permeability) rigorously masked.

Step 2 — Matrix assembly. Assembled sparse transmissibility (T), accumulation (B), source (Q), and well productivity (J) matrices. Used harmonic mean permeability averaging for transmissibility calculations.

Step 3 — Implicit solver. Solved the diffusivity equation implicitly via sparse matrix inversion at 1-day timesteps over a 201-day forecast horizon, ensuring unconditional stability.

Step 4 — Well modeling. Implemented Peaceman well model for BHP-controlled producers and constant-rate injector. Captured well-to-well interference, skin effects, and dynamic productivity index evolution as reservoir pressure depletes.

Step 5 — Validation. Cross-validated numerical pressure profiles against the line-source analytical solution (exponential integral / Ei-function) for radial flow, ensuring code verification and benchmarking accuracy.

Key parameters
Grid: 54 × 22 (1,188 blocks)
Reservoir: 7,060 × 5,753 × 100 ft
Timestep: 1 day
Forecast: 201 days
Wells: 1 injector + 5 producers
Boundary: Mixed (rate + BHP)
Validation metrics
Analytical: Ei-function (Theis)
Flow regime: Radial
Agreement: Numerical vs. analytical
Method: Line-source solution
Purpose: Code verification
Status: Validated

[Figure 1: 3D pressure surface plot — Nechelik Field at 100 days]

[Figure 2: 2D pressure contour map — multi-well interference pattern]

[Figure 3: Rate-decline curves — 5 producers + 1 injector]

Results & deliverables
 
• Time-dependent well rates for all 5 producers under BHP control
• Injector bottom-hole pressure response over 201 days
• Cumulative oil production (Np) for reserves estimation
• 3D pressure surface plots for visual communication
• 2D contour maps showing drainage patterns and interference
• Rate-decline curves for production forecasting and development planning
Impact
 
The Nechelik simulator is now used as a training case study in GSERC internship programs and as a decision-support prototype for African operators evaluating well spacing and drainage strategies. It demonstrates that world-class reservoir simulation is achievable with open tools and rigorous validation — no commercial licenses required.