Q: Can a slot be cut with a certain dipping ( i.e. parallel to formation dipping) at a certain angle?
Generally a PowerSlot can be oriented in any direction. In some wells if this means that dipping = “azimuth”, then the answer is yes, the slice can be cut with a certain dipping. Without optional services, the PowerSlot machine is limited to orientation whereby one plane is parallel to the well-bore direction at all times.
Q: How you control the depth of cut?
There are two different ways to control the depth of cut: Design and Calibration.
Design: Nozzle parametrics determine the focus and shape of slice. We have various nozzles from which most appropriate nozzle is selected as part of our work over plan.
Calibration: The equipment is per-calibrated before it is lowered into the well with the parameters of the planned slice. The equipment cannot cut beyond the set parameters.
The operator adjusts cutting speed, abrasive concentration, working pressure, and fluid rate to ensure that the slice is proceeding as planned and confirms the slice with real-time reports.
Q: Does PowerSlot tool have the ability of making 2 sets in one run at different depth?
Yes, the tool can make two sets of cuts at different depths. Slotting of multiple intervals is achieved by:
1. The tool is calibrated for multiple cut parameters.
2. The tool is positioned at the deepest interval first.
3. Tool is moved upward to the next position; this process is repeated as often as is necessary to slot the various intervals.
Q: Regarding the slurry used to do the excavation, will it be brought up to surface or remain in the formation. If up to the service, how will it be done?
All slurry returns to surface. Slurry travels down to target interval through tubing, CT, or drill pipe. Slurry cuts window in casing, cement, and formation. Window shape has x, y, and z planes. Cuttings and slurry returns back up to surface through annulus. Pressure in the formation is determined before beginning of operation. Operation is planned so that formation pressure always exceeds hydrostatic pressure in annulus. So, absolutely no slurry is injected at any point into formation, and no cuttings can stay in formation. (Cutting sand is usually • lb. to • lb. per gallon of cutting fluid)
Q: How are the cuttings and excavated material brought to surface?
Cuttings always return to surface. For example in a 5-inch well-bore (we can use any casing size as long as it exceeds 4 inches ID), the speed of the returning slurry is approximately 25-28 mph or 40-45 km/h.
For cuttings to stay in hole, the downward force of cuttings must exceed the upward force of slurry returning to surface. Slurry travels upwards at 40-45 km/h in annulus. Opposing or downward force of the cuttings cannot resist the force of the returning slurry. Gravity = 8 m/s x 60 sec. x 60 min x 0.1 gram = 28.8 km/h. The cuttings travel to the surface at the net rate of 15-18 km/h and get dumped in filtration and pit. If there is a concern that casing size is too big (fear that cuttings will not rise), or for formations is too high porosity (fear that formation will absorb fluid), N2 foam can be added to slurry to make hydrostatic even lighter. This is all per-calculated.