 |
Gas Reservoir Quality |
| |
- Zone thickness, porosity and areal extent (logs)
- Shaliness, swelling or migration of clays
- No oil production being produced into the wellbore
|
| |
Gas and Water Contact |
| |
- The present amount of water
- The barrier separating the gas and water portions
|
| |
Nature and Size of Gas Trap |
| |
- Single or multiple well prospects
|
| |
Reservoir Targets |
| |
|
| |
Water Disposal Zone(s) |
| |
- A disposal zone must be below the bottom of the
production zone by at least 16 meters
- The PBTD of the well bore must be to a depth that
is sufficiently below the bottom production zone
and is sufficient to set and cement production casing
or a liner into or through the disposal zone
- Additional rat hole or a sump below the injection
perforations is desirable to allow production formation
debris or particles to settle out and to be stored.
- The disposal zone must be compatible with the
disposal fluid
- The disposal zone must be able to adequately accept
the water associated with the gas production and
flow into the disposal zone under fracture or regulation
pressure
- There has to be a geological barrier between the
production and disposal zone(s)
- There has to be a mechanical barrier (cement seal)
between the production casing and the geological
barrier
|
| Well Performance Factors |
|
|
| |
DST/Flow Test Results |
| |
|
| |
Productivity of Surrounding Wells |
| |
- Gas rate and cumulative recovery
- Decline curve and behavior
- Past produced water problems - how much - what
was done with the produced water
- Hours on production
- Logs
|
| |
Remaining Recoverable Gas Reserves |
| |
|
| |
New Well or Re-Entry Candidate |
| |
- Age and condition of well
- The production casing must be free from holes
or perforations that can thief the gas or communicate
other fluids
|
| |
Depths |
| |
|
| Operational Factors |
|
|
| |
Infrastructure |
| |
- Adequate pipelines, storage, gas treatment and
compressors
|
| |
Regional Operating Issues |
| |
|
| |
Production Casing Size |
| |
- 4.5" or greater for <500 barrels of water
per day (BWPD)
- 5.5" or greater for 500 to 1,000 barrels
of water per day (BWPD)
|
| |
Potential Problems to Watch For |
| |
- Sand or other particles
- Casing leaks
- Corrosion
- Severe wellbore deviation
|
| DGWS Equipment Parameters |
|
|
Critical to the selection of a DGWS system
is the availability, durability and versatility of the
equipment as well as the economics involved in the initial
installation and subsequent maintenance of the ultimate
system.
DHI addresses the following questions when selecting
a DGWS system: |
| |
- Does the client have surface equipment at their
disposal and if so can DHI adapt it into the design?
- Is it geographically difficult to perform specific
services on the wellsite?
- Is the aesthetic value of the surface critical?
- Are repair services available at the wellsite
and of what type?
- At what degree can the proposed DGWS system handle
changing conditions?
- Is the well easily assessable for a pumper?
|
| In summary, determining which method of
DGWS system is most economical and applicable for a
particular well, it is essential that the above prime
factors be taken into careful consideration. |
