neqsim-reservoir-history-match-forecast

Reservoir History Match and Forecast

A reservoir model cheap enough to re-match whenever new data arrives, with a compositional fluid, that feeds the process model with the fluid the wells actually produce.

When to Use

• A gas or gas-condensate field with several formations, compartments or wells must be matched to its production history and forecast.
• The produced composition changes with depletion and the process model should see it.
• Production and composition must be shown for history and future through a process model.
• Not for black-oil or volatile-oil reservoirs with mobile oil (use the grid route in neqsim-near-well-and-injectivity) and not for open-data volume screening (neqsim-reservoir-model-builder).

Inputs

• Daily well gas, condensate, water, on-stream hours, wellhead pressure, downhole pressure.
• Field allocated gas, condensate and water series.
• Well-to-formation and compartment map; initial pressure and temperature per tank.
• Tuned reservoir fluid per formation (NeqSim EOS, component names, heavy indices).
• Scenario: target rate, minimum wellhead pressure, well schedule.

Outputs

• Matched tank parameters (giip_gsm3, aquifer_c, cgr_scale, heavy_scale) with std and bound hits.
• Match quality by observation kind and tank.
• Well deliverability (a, c) and water-gas ratio.
• Produced composition and condensate-gas ratio versus date and pressure.
• History and forecast tables per tank and well; P10/P50/P90 when identifiable.
• Wellstream tables (composition, molar rate, water, WHP) for process models and process KPI series.

Engineering Method

Model. A tank is one reservoir, formation or pressure compartment with its own fluid, volume (giip_gsm3, wet gas in place as standard gas volume), optional Schilthuis aquifer (aquifer_c) and a condensate-yield scale (cgr_scale). The depletion path (DepletionPath) is a constant-volume depletion on a NeqSim EOS: moles left, liquid saturation, produced-stream composition and surface yield versus pressure. It depends on pressure only, so it is computed once per fluid and the material balance looks pressure up from cumulative moles produced. A well has deliverability P_res^2 - WHP^2 = a q + c q^2 fitted from daily history and a share of each tank it drains. A field is tanks + wells + optional tank connections. History is driven by well gas rates; the forecast takes min(target, sum of well capacities at the minimum wellhead pressure).