Before we get into types of completions, let’s remember two things: 1) horizontal wells have relatively shallow entry angles (usually from 0° to about 25° above horizontal), and 2) most, if not all, wells will need some sort of rehabilitation during their useful life. Why are these two points important? At some time in the future, you may need to access the well to pull a pump or injection tubing, perform a video survey and/or jet the well screen. Because the well exits the ground at a shallow angle, the surface completion should be designed with future access in mind. In other words, long, skinny vaults may be a better choice than a traditional, small, round completion.

To the right is an example of a horizontal sparge well with a flush mount completion. Note that the box is longer than it is wide. Also notice that the 4” HDPE casing terminates in the vault with a “Y”. One end dips into the ground and connects to the sparge blower. The upper side of the “Y” is capped and set up as a clean out port. The cap can be removed, and a rig or jetting truck can easily access the well for video or rehab activities.

Horizontal wells with above ground completions are a small percentage of our total installations. Many of these completions are for wells where submersible pumps are installed, or the well is utilized for industrial or municipal water supply. Complex instrumentation and controls, power drops, flowmeters and even sample taps are difficult to place below ground and access. That makes above-ground surface completions the go-to standard for pumping wells. Well access is certainly easier; the above-ground piping can be easily accessed, and a rig can be placed directly behind the well for rehabilitation activities.

Some of our environmental remediation horizontal wells are placed in complicated areas requiring innovative surface completions. For example, in 2018, Ellingson-DTD crews completed two wells in a downtown area of a large West Coast city. The wells are being utilized for both dual phase extraction and injection for a UST leak clean up. The rig up area was extremely tight on a narrow sidewalk, squeezed between a multi-story building and the street. This required the crew to drill both wells, blind (single-ended) completions with a total length of roughly 140’, from the same small entry pit in the sidewalk. The final surface completion had to include both wells, be flush to the sidewalk, securable, and stable for foot traffic.

Finally, sometimes things really get weird… This is a particularly complicated surface completion. The long, blind single-entry well is used for groundwater containment at an industrial site. The wellhead surfaced in a high-traffic area and the groundwater level was nearly at the ground surface. This is sort of a combination completion, both above and below ground, protected from traffic by very stout bollards. The field crew called this one the “Bomb Shelter”.

Many times, we recommend that the consultant contact a local contractor to complete the well head. It is most efficient for the surface completion to be constructed when the well is connected to the treatment system, and those connections typically get installed long after the well has been drilled. Especially for flush-mount style completions, it is easier to make the subsurface connections before or during the vault construction, rather than dealing with going under the vault’s concrete apron. So, it’s just easier for whatever contractor is making those connections to also build the vaults after they’re done.

There you have it, a short synopsis of the different options you can choose from to complete wellheads for horizontal wells. We can complete the installations as flush mounts, above grade, or combinations of both. We can be as creative as you need for the specific site conditions, but please remember, bigger and complicated means expensive and time consuming. It really all depends on what connections you plan to make, and that probably means we won’t even be involved.