Performing an Analysis

Custom (IHS DeclinePlus)

Useful for creating custom worksheets of unique combinations of data from templates created in the Diagnostics tab. Custom worksheets can contain both purely diagnostic data, and data that can be analyzed (typically for Decline analysis methods).

Decline (IHS DeclinePlus)

Decline analysis is an empirical analysis and forecasting method based on Arps equations. Traditional decline analysis is a conventional method for forecasting production and estimating expected ultimate recoverable (EUR) reserves. It is generally accepted that Arps equations should be used only during the boundary-dominated flow period when operating conditions are constant. However, the development of tight and unconventional reservoirs has seen the widespread use of Arps during transient flow periods. Revised techniques such as the Modified Hyperbolic decline (which limits the decline factor to a minimum rate), multi-segment decline, and the stretched exponential decline attempt to limit the impact of the hyperbolic b factor to make the projected EUR more reasonable.

FMB (IHS RTA / IHS CBM)

Flowing material balance (FMB) analyses use reservoir performance flow data, production rates, and flowing pressures to evaluate original hydrocarbons-in-place. The flowing material balance is a good alternative to the conventional static material balance method for estimating hydrocarbons-in-place when there are limited or no static pressure measurements, and when the reservoir connectivity is well understood. This method is applicable to conventional oil and gas reservoirs, as well as dry or dewatered CBM reservoirs.

Forecast (IHS DeclinePlus)

The forecast worksheet displays production forecast analyses in a table. Forecasts can generally be displayed in daily, monthly, or yearly forecasts and can be exported in any of these period formats. Secondary forecasts can be generated from existing forecasts with your specified ratios, including GOR (gas-oil ratio), WOR (water-oil ratio), NGL-gas (natural gas liquids-gas) ratio, CGR (condensate-gas ratio), propane-gas ratio, butane-gas ratio, and WGR (water-gas ratio).

Gas AOF / TPC (IHS VirtuWell)

The Gas AOF / TPC analysis creates tubing performance curves (TPCs) for a gas well, and overlays them on the sandface absolute open flow (AOF) curves. This is very useful for designing tubing strings and optimizing production rates.

Hybrid (Beta) (IHS RTA)

The hybrid model is essentially a numerical model, but with certain modifications to significantly reduce computation time, so that it is almost as fast as an analytical model.

Material Balance (IHS DeclinePlus / IHS CBM)

Oil Material Balance is a performance-based method used to interpret, analyze, and model static pressure and production data from oil reservoirs in order to determine pool groupings, original oil-in-place (OOIP), gas cap size, drive mechanisms, and a theoretical recovery factor.

Gas Material Balance is a performance-based interpretation method used to determine original gas-in-place (OGIP) based on production and static pressure data. It relates the original gas in the reservoir to the production volumes and current pressure conditions and fluid properties.

CBM Material Balance is a performance-based interpretation method used to determine original gas-in-place, both free and adsorbed (OGIPF and OGIPA), based on gas and water production and static pressure data.

Numerical (IHS RTA / IHS CBM)

Numerical models simulate multiphase flow situations in the reservoir. Numerical models can also be used to enhance the modeling exercise when more detailed reservoir data is available in more complicated cases.

Oil IPR / TPC (IHS VirtuWell)

The oil IPR / TPC analysis creates tubing performance curves (TPCs) for an oil well, and overlays them on a sandface inflow performance relationship (IPR) curve. This nodal analysis tool is useful for designing tubing strings and optimizing production rates.

Pressure Gradient (IHS VirtuWell)

Flowing pressure gradient analysis is intended for use when fluids (gas, oil, and/or water) are moving through the flow path specified in the wellbore configuration.

Probabilistic & Sensitivity (IHS RTA/ IHS CBM

Probabilistic analysis (also known as Monte Carlo simulation) quantifies the impact of uncertainties on output variables and determines the range of probable and most likely outcomes.

Sensitivity analysis determines which input parameters create the largest response in outputs. This is achieved by systematic investigation of the reaction of the simulation outputs to extreme values of the model’s input.

PSS Model (IHS CBM)

Psuedo-steady state (PSS) models simulate CBM (coalbed methane) vertical reservoirs and hydraulically-fractured reservoirs. You can obtain reservoir parameters by history matching to gas rates, water rates, and sandface flowing pressures, and generate two-phase (gas + water) forecasts.

• Single-layer PSS
• Multilayer PSS

Ratio Analysis (IHS DeclinePlus)

Ratio analyses identify trends in the relationship, or ratio, between two fluids. This trend can then be used to create rate forecasts of the individual fluids.

Water-Oil Ratio (WOR) is a performance-based empirical analysis method of trending future water production for the purpose of forecasting oil and water production and determining EUR.

Oil Cut is a straight-line forecast on oil cut vs. time. It cannot provide an EUR estimate until linked to the total fluid rate.

Surveillance (IHS DeclinePlus)

Surveillance analysis facilitates understanding of reservoir performance and identifying opportunities to improve ultimate recovery.

Hall Plot analysis enables users to draw conclusions about average injectivity performance.

VRR analysis aids in identifying parts of a field where increasing or decreasing amounts of water must be injected in order to reach or maintain VRR targets.

Type Well (IHS DeclinePlus)

With the type well analysis, you can create a traditional decline analysis for the average production of a group of wells. This analysis technique is useful for generating a forecast for a well that has little or no historical production data.

Typecurve (IHS RTA / IHS CBM)

Agarwal-Gardner estimates in-place fluid volumes, drainage area, reservoir permeability, skin around the well, or fracture half-length / fracture conductivity for hydraulically fractured wells.

Blasingame estimates skin, formation permeability, in-place fluid volumes, and reservoir drainage area. Blasingame has several families of advanced typecurves such as finite conductivity, elliptical, water drive, and open-hole horizontal well in addition to classic radial and fracture typecurve models.

Compound Linear well-suited for analyzing horizontal multi-fractured wells drilled in tight gas or shale reservoirs.

Fetkovich estimates expected ultimate recovery (EUR), skin, and formation permeability from the rate history of the well.

NPI is the inverse of the Agarwal-Gardner typecurves. This analysis method is often preferred by those who come from a pressure transient analysis domain. Outputs are the same as Agarwal-Gardner.

Transient is useful for datasets containing long-term transient flow. Outputs are the same as other modern typecurve match techniques.

Wattenbarger is well suited for reservoirs that exhibit a long-lasting transient linear flow regime. This method is particularly useful for the analysis of tight and shale gas wells.

Unconventional Reservoir (IHS RTA)

The unconventional reservoir model (URM) interprets the linear flow signal exhibited in multiple-stage hydraulically fractured unconventional reservoirs and forecasts production from such reservoirs.

Volumetrics (IHS DeclinePlus / IHS CBM)

Volumetrics analysis estimates the original hydrocarbon fluid volume in a reservoir. This analysis requires knowledge of reservoir rock properties as well as fluid saturations and properties.