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

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

Lease status

• 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

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

Geological description for each zone

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

Environmental concerns

• 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

• 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

• Contact list with addresses and phone numbers
• Reporting requirements for partners

Data collection

• 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

• 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

• 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

See also

• Introduction to wellsite methods
• Wellbore trajectory
• Conventional coring
• Drilling fluid
• Land rigs
• Rig personnel
• Wellsite math
• Mudlogging: equipment, services, and personnel
• Wellsite safety
• Offshore rigs
• Well types

External links

find literature about Well planning

• Original content in Datapages
• Find the book in the AAPG Store
• Well planning on PetroWiki

total depth

measured depth

true vertical depth

revolutions per minute

bottom hole temperature

drill stem test