Lurking deep in a wellbore, built up solids and fluids can create headaches for producers. This type of situation can lead to a rapid decrease or complete loss of production while producers are unaware of the specific cause.
Even worse, with todayâ€™s high capital cost per well and complex well designs, some producers are seeing abnormal declines in relatively new plays. These declines can create concern for the reserves estimates and overall recovery of a particular pool.
In the past, speaking primarily about vertical well types, producers have had a toolbox of technologies at their disposal, such as production logging. But, it is virtually impossible to production-log non flowing horizontal oil wells in the Western Canadian Sedimentary Basin for a variety of reasons.
With the lack of technology in this field, producers often struggle to understand the relationship between the reservoirs and horizontal well designs. Producers can now get a clearer picture as to what is happening downhole, which, according to Quantum Downhole Systems Inc., is critical to be able to make better decisions and improve their effectiveness in a given play.
To help accomplish this, the Calgary-based company has created a new JetVak system, which incorporates a newly designed coiled tubing system and a specifically engineered jet pump. The company has been proving the technology over the past 4 years. Its client list includes many of the whoâ€™s who of the oil patch, including Husky Energy Inc., Shell Canada Limited, ConocoPhillips, Devon Energy Corporation, Chesapeake Energy Corporation, Cenovus Energy Inc., and Penn West Exploration.
â€œQuantumâ€™s unique technology, one of only two in the world, not only cleans out wells but gathers valuable data that can help producers optimize drilling and completions strategiesâ€, explains Steven Winkler, who is Quantumâ€™s president and general manager. Dan Bosilca, a senior completions engineer with Shell, says his company used the JetVak technology in a pair of wells in Alberta last summer. â€œWe believe this is good technology, and it has a lot of potential for these very low-pressure reservoirs,â€ he notes. â€œ[In the first well] the results were very promising. We did clean up a lot of sand from that wellbore. The second one was basically almost the same story.â€
Cleaning the well allowed the company to take steps to improve production. â€œOf course, thatâ€™s the goal,â€ Bosilca says. â€œThe thing is, most of these wells are quite old. They are long horizontals, and they have slotted liners.
â€œItâ€™s heavy oil so they do produce some fines. Of course, in time, these wells will basically plug off or the flow will be diminished. In the future, we are looking to use this technology again.â€
The technology was designed to address many problems associated with the development of under or sub-pressured reservoirs and the differing needs of horizontal well designs versus verticals are becoming the norm in western Canada-horizontals.
â€œWe recently learned of a study from the Alberta Research Council that proved to us why we see so much sand in the liners of horizontal wells. The fluid rate required to keep sand or solid particles in motion during production in a 114-millimetre liner is approximately 1,000 cubic meters per day,â€ Winkler says.
â€œTo compound this problem, when these wells are fracked and then flowed back, the heel zones/ stages tend to out compete the mid or toe zones/ stages,â€ he says. â€œThis is where the velocities are quite often below the required rate of 90 centimeters per second.â€
The two primary functions of the JetVak downhole pump are to create simultaneous jetting and vacuuming. The high-pressure jets are used to fluidize the sand or break through solids bridges in the liner. The vacuum is created by the Venturi effect.
The wellbore fluid and solids are returned to the surface via the second coil conduit in the FlatPak. During this process, the well is in a neutral or underbalanced state. This process allows Quantum to recover a higher volume of sand per well versus conventional techniques, as well as pinpoint zones or stages that are producing sand into the wellbore. â€œItâ€™s a â€œclean-as-you-goâ€™ approachâ€, Winkler says. Conventional cleanout processes use circulation of high volumes of fluid, nitrogen, or foam. This creates an overbalanced effect on the wellbore, which pushes some of the solids back into the formation. According to Quantum, these processes are ineffective, expensive, and time consuming. The companyâ€™s on-site technician may alter the speed of the FlatPak based on solids returns and deviation survey information.
Quantum has completed roughly 600 operations in many of the hot plays in western Canada and the United States, including oilsands steam assisted gravity drainage (SAGD), cold heavy oil production with sand, Montney oil, and Slave Point and the upper Bakken formations and the Viking.
The company has recently been doing many production evaluations on horizontal wells adds Winkler. Because of this, Quantum has developed an isolation system that utilizes inflatable packers in combination with a modified jet pump. Information such as stage-by- stage oil/water/gas/sand ratios can be cross-referenced with producing bottom hole pressure and temperature information.
This data helps create an accurate economic model for the well and may result in higher well productivity, improved fracture treatments, and higher overall reserves.
â€œIf you ask engineers whether the wellbore is clean, 99 out of 100 are going to say either â€˜I donâ€™t knowâ€™ or â€˜probably not,â€â€™ Winkler says. â€œThe next step to that is to ask how do you understand your reservoir if the mechanics of the system are not clean?
â€œItâ€™s the same with your heart and your veins. Your heart has to work that much harder when your veins are plugged. Or, is it really your heart that has the issue? Youâ€™ve got to find out all of the information prior to making a sound decision. Weâ€™ve got a tool that will help find this information, and thatâ€™s why we came up with it.â€
Winkler referenced specific wells, one in the Lloydminster, Alta. region, where 600 meters of drilling fluid was seen during the cleanout. This came out of a well that had been on production for 10 years. Another well in the Wabasca polymer flood area gave up eight cubic meters, or 17,000 kilograms, of sand.
Recent changes include the transition from the FlatPak which was our conveyance system up to the third quarter of 2013. We are now using an all steel Dual Coil deployment system that offers many improvements and allow us to work on deeper/longer and hotter wells.
A second technology Quantum is working on is a new jetting system designed to reduce the amount of runs required in a well when production testing is part of the program as well as increase the jetting flexibility, especially when using chemicals or acids.
Quantum, as a small 4 and a half year-old company, is also embarking on what Winkler calls a massive task. â€œConvincing the industry that we so far, know little about horizontal wells. It is unchartered territory,â€ he says.