Well planning

	Development Geology Reference Manual
Series	Methods in Exploration
Part	Wellsite methods
Chapter	Well planning
Author	Arnold M. Woods, Byram Reed
Link	Web page
Store	AAPG Store

Planning a well is an iterative process between geoscience and engineering staffs that involves frequent accessing of several databases and clear communication. Three basic areas need to be examined in planning a well:

What target(s) will be evaluated?
How will the well(s) be drilled to reach those target(s)?
How will the target zone(s) be evaluated?

For the development geologist, well planning includes verifying numerous points under a variety of general headings. This chapter provides a reasonably thorough checklist of those areas that should be investigated when planning a well.

Wellsite data package[edit]

A data package should be prepared for use on the wellsite containing all of the data needed for correlation and evaluation. This includes maps, offset well logs, the well prognosis, and any other data that the geologist believes may be useful. Only copies (not the originals) of these data should be taken to the field.

Well planning checklist[edit]

Lease status[edit]

Ownership
Limitations (e.g., oil rights down to a certain formation; gas rights below a certain level)
Nearby acreage availability (to extend play)
Well permit filed with state?
Survey (lease lines, ground elevation)
“Legal” well location

Geological and economic justification[edit]

Anticipated pay zone(s)
Anticipated pay type(s) (e.g., oil, gas, CO₂)
Economic reserves
Economic scenario(s)

Geological description for each zone[edit]

Name
Age
Depth
Thickness Structure
Lithology
Secondary and exotic minerals
Porosity and permeability

Environmental concerns[edit]

Weather
Topography (e.g., is proposed location in a streambed?)
Environmental Impact Statement (EIS) needed?
Cultural hazards and considerations
Accessibility
Safety hazards (training needed?)

Drilling program[edit]

Straight, slanted, or horizontal well
Anticipated total depth (TD) in measured depth (MD) and TVD (true vertical depth)
H₂S and other gases
Over- and underpressured zones
Casing points
Drilling problems
- Sloughing shales
- Swelling shales
- Salt beds
- Faults
- High angle beds
- Lost circulation zones (e.g., fractures, excessive mud weight)

Communications for operators and partners[edit]

Contact list with addresses and phone numbers
Reporting requirements for partners

Data collection[edit]

Mud logging
- Crew size and services to be provided
- Number of sets of each type of sample
  - wet
  - dry
  - geochemical
  - paleontological
- Pressurized unit
- Hot wire or flame ionization detection (FID) chromatograph
- Bit dulling plot
- Overpressure plot
- Rate of penetration (ROP), weight on bit (WOB), pump pressure (PP), revolutions per minute (RPM), and bit data
- Mud data
- Pit volume monitors
- Special analyses
  - ion tracing
  - radioactive monitoring
  - shale densities
  - d and dc exponent
  - hydrogen sulfide (H₂S) detectors
- CRT displays on rig floor, company representative's office
Electric logging
- Big, regular, or slim hole tools
- Temperature requirements
- Fresh, salt, or oil mud tools
- Tool combinations and order of logging runs (usually gamma ray, deep resistivity, porosity, sonic, pad-type resistivity, dipmeter, checkshot survey, and sidewall cores)
- Backup tools
- Calibration, both at surface (before and after logging) and downhole
- Repeat and overlap sections
- Scales
- Check shot survey points (determined after first logging run)
- Bottom hole temperature (BHT) with each tool
- Maximum logging speeds
- Magnetic tape requirements (e.g., 800 or 1600 bpi)
- Display format
Fluid samples
- Repeat formation test (RFT) and drill stem test (DST)
  - Interval(s)
  - Packer seats
  - Sampling method
Coring
- Conventional, wireline, and/or sidewall
  - Formations automatically cored?
  - Core on show?
  - Core handling procedures

Data distribution[edit]

Types of data
- Drilling records (e.g., bit record, geolograph charts)
- Mudlogs and mudlog records
- Electric logs
- Core and/or cuttings (wet and/or dry)
- Fluid samples
- Pressure charts
- Laboratory analyses
  - cuttings
  - cores
  - biostratigraphic
  - geochemical
  - fluid properties
Number of copies of each type of data for
- Division office
- Headquarters office
- Partners
- Federal and state agencies
- Wellsite copies
- Geologist and geophysicist
- Drilling engineer
- Reservoir engineer

Sources of data for well planning[edit]

Offset wells
- wireline logs
- mudlogs
- daily drilling reports
- velocity surveys
- bit records
- scout tickets
- paleontology and geochemistry reports
- production data
State agencies (e.g., Railroad Commission in Texas)
Industry libraries (e.g., Petroleum Information [PI], Dwights)
Service companies
Literature search

External links[edit]

find literature about
Well planning