Five basic types of major reservoir data are provided in the Significant Oil and Gas field of the United States Database: (1) rock and fluid characteristics, (2) discovery well, (3) production and reserves, (4) oil-in-place and gas-in-place, and (5) post-primary recovery method. Each is listed in detail as follows:
Major Reservoir Rock and Fluid Characteristics
There are four types of major reservoir rock and fluid characteristics variables: reservoir identification, reservoir volumetric, other reservoir rock, and reservoir fluids.
The reservoir identification variables are:
- Unique field identification code, field name, and state/district code
- Reservoir age rank and formation code
- Reservoir composition and number of pools
- Play codes from Nehring Associates (NRG), U.S. Government (USG, incorporating both the USGS (onshore) and MMS (offshore) play definitions), and Gas Research Institute (GRI)
The reservoir volumetric variables are:
- Thickness
- Area
- Porosity (average, maximum, minimum, and type)
- Initial oil, gas, and water saturations
- Formation volume factors of oil and gas
- Gas compressibility
- Temperature
- Initial pressure
The other reservoir rock variables are:
- Lithology
- Depth to top
- Permeability (average, maximum, minimum, and type)
- Tight formation indicator
- Natural drive mechanism
- Residual oil saturation
- Well spacing and number of developed spacing units
- General and specific trap type
The reservoir fluid variables are:
- API gravity of fluids
- Crude oil viscosity and pour point
- Crude oil sulfur content
- Gas-oil ratio
- Gas gravity and heating value
- Composition of reservoir gases
- Resistivity of formation water
Major Reservoir Discovery Well
The major reservoir discovery well information in the database identifies each major reservoir discovery well and indicates who drilled it, where and when it was drilled, and what the results of this drilling were. The major reservoir discovery well variables are:
- Unique field identification code, field name, and state/district code
- Reservoir age rank and formation code
- API well code
- Lease name and well number
- Original operator name and code
- Location (lease, block or section, township, and range)
- Elevation and water depth
- Spud, rig release, and completion dates
- Total depth and formation at total depth
- Productive formation(s) and interval(s)
- Initial potential(s)
- Well type (new field or new pool discovery)
Information on productive formations, producing interval, and initial potentials are provided for as many as three different formations, beginning with the formation of the reservoir discovered by the well and proceeding by descending depth for the other formations.
Major Reservoir Production and Reserves
The database provides two types of major reservoir production and reserves information. Variables for major reservoir production and reserves by product include:
- Unique field identification code, field name, and state/district code
- Reservoir age rank and formation code
- Annual production, cumulative production from inception, proved reserves, and known (ultimate) recovery of crude oil, natural gas (dry), and natural gas liquids, 1982 to the present
The production and reserves information by product are combined into a total recovery table which indicates major reservoir size in barrels of oil equivalent (BOE) with the following variables:
- Unique field identification code, field name, and state/district code
- Reservoir age rank and formation code
- Cumulative production from inception, proved reserves, and known recovery (total reservoir size), expressed in liquids and liquid equivalents (BOE), 1982 to the present
- Reservoir size classification (expanded AAPG and geometric)
- Reservoir producing status (producing, shut-in, abandoned, or gas storage)
- Reservoir type (oil, gas, or combination)
- Reservoir size rank (for fields with more than one major reservoir)
Here, as elsewhere in the database, gas is converted to its oil equivalent at a rate of 6000 cf/bbl.
Major Reservoir Original Oil-in-Place and Gas-in-Place
The database provides information on both original oil-in-place and original gas-in-place for major reservoirs.
The major reservoir original oil-in-place variables are:
- Unique field identification code, field name, and state/district code
- Reservoir age rank and formation code
- Major reservoir original oil-in-place (OOIP)
- Source, year, and quality of OOIP estimate
- Current oil recovery factor
The major reservoir original gas-in-place variables are:
- Unique field identification code, field name, and state/district code
- Reservoir age rank and formation code
- Major reservoir original gas-in-place (OGIP)
- Source and year of OGIP estimate
- Current gas recovery and shrinkage factors
The gas-in-place data are available only for the Gulf of Mexico OCS.
Major Reservoir Post-Primary Recovery Methods
The major reservoir post-primary recovery methods variables are:
- Unique field identification code, field name, and state/district code
- Reservoir age rank and formation code
- Sequential order of recovery method
- Recovery method and the extent of its application
- Year method was initiated and current status of method
Post-primary recovery methods data are provided only for oil reservoirs
The five basic types of reservoir data are combined with the general field information table and the New Fields table to create the reservoir master table (RMASTER). This table is designed to facilitate a broad variety of reservoir data retrievals.