Video logs help water well professionals in assessing the internal condition of a well.
By Christopher S. Johnson, PG, CHg
Run and see is an apt description of the advantage afforded to water well contractors and scientists by the introduction and continuous advancement of video logging equipment specifically designed for inspecting and assessing groundwater wells.
In general, the greatest application of water well video logging has been in the assessment of well condition, relative to declining well performance—such as loss of well yield, sanding, or changes in water quality.
A video log has become an indispensable tool for looking at and understanding what has happened to a well as it matures. Wells do mature, and as they do, they can become plugged, blocked, fouled, broken, leaky, and nearly any combination of those conditions. Just as modern medical equipment can aid doctors in assessing the internal workings of humans, so can video logs help water well professionals in assessing the internal condition of a well.
[not_logged_in]Login with your NGWA member account to read the full article.[/not_logged_in]
Video logging has tremendous benefits, particularly when employed in a specific and consistent manner. Video logging is now being used to verify construction and integrity of newly completed well, along with assessing the structural integrity and performance condition of existing wells.
With that said, it is vital video logging be done in a proscribed and consistent manner, to reduce the risk of missing something important.
Situations for Video
New well construction video logging involves accurately documenting the construction of the well, identifying concerns (e.g. leaking well seams), and establishing a baseline condition of the well for future reference. Existing well video logging often focuses on determining the source or sources of problems identified with well performance, pump performance, or water quality.
There is one more unique situation in which well video logging can be employed, and this particular application is at the heart of getting a good start on a great well.
Normally, at the completion of well construction, the drilling contractor will engage in some form of rig-based well development. This rig-based development is recognized as the single most effective means of developing a new well, based on the ability to reach all depths within the well with the most applied energy. This initial development is thought to remove the most viscous drilling fluid remnants and begin moving fluid through the open are of the well casing.
Arguably, this initial development is the most critical portion of bringing a new well online. Removing residual drilling fluid within the well, within the gravel pack, and that which has invaded the formation is critical to well performance, longevity, and energy efficiency.
With that said, how can we know when “enough is enough?” As in, has the drilling contractor removed as much of this residual material as is technically and economically feasible?
Let me address the economics of initial well development first. The money spent by a well owner in obtaining the greatest degree of effective and efficient well development immediately after well completion will be repaid for years in energy cost savings from a more efficient well, and maintenance cost savings from a properly developed well.
Now for the technical feasibility of assessing when this initial well development is complete. Traditionally, some arbitrary amount of hours has been assigned with general parameters such as “clear water” or “low turbidity” being employed. On occasion, it’s even simpler, in that the cost estimate included 12 hours and the contractor put in 12 hours regardless of the condition of the well.
For many years now, I will have the drilling contractor include on their cost estimate “additional initial development/rig development” as a per-hour charge. This lets the well owner know there may be more development necessary based on my interpretation of—you guessed it—the video log! Yes, I have the well contractor video log the well post rig-based development and before they move the rig off from over the new well.
Many have said I wouldn’t see the open area of the well, but my counter was always “you developed it, right?” These videos generally reveal a good, clean open area, and the project can move forward.
However, and this is more common in the last several years, as a result of the drought-induced pace of well completions, I have seen many wells that range from “just a little more” to “totally inadequate development.”
The former is the domain of good contractors using good techniques and the well just needing a few more hours of work. In that situation I advise my clients to pay the well contractor for the extra effort because as I previously said, it is a sound investment.
The latter condition is often the result of haste, incorrect means and methods of development, or both, and is the responsibility of the well contractor. I tell both the contractor and the client additional development is needed, and the client should not pay for it.
Also Aids Pump Contractors
Another contractor who benefits from this is the pump contractor. Many times, my pump contractor clients have come to me with after-the-fact videos of plugged wells which should have been addressed by the well contractor.
One of my best pump contractor clients has taken this and established a procedure that any new well they are hired to pump develop, they video log first. This avoids any question about the condition of the well before they started their development efforts. Unfortunately, for the well owner, the well contractor is long gone, and might prove difficult in getting back to address the issue.
So, my final thought is to urge you to position yourself to get paid for warranted extra development, and video log the well post rig-based development to answer the “enough is enough” question.
Christopher S. Johnson, PG, CHg, is the president and principal hydrogeologist at Aegis Groundwater Consulting LLC in Fresno, California. Johnson works with well owners and operators on a variety groundwater-related projects, including locating new water resources, well design and construction management, aquifer testing, and well rehabilitation. He can be reached at firstname.lastname@example.org.