A multifinger caliper records the internal shape of casing or tubing. Its mechanical measuring fingers follow the accessible inner surface, producing information about enlargement, restriction and other departures from the expected profile. That makes it useful for investigating internal damage, but an internal measurement does not reveal every condition of the steel surrounding it. [1, …
A step rate test and an injectivity test can both involve pumping into a well, but their names do not establish the same interpretation. An injectivity assessment asks how the exposed formation accepts fluid under stated conditions. A stepped-rate assessment examines how the pressure response changes as the injection rate changes. The latter can form …
Wellbore cleanout before recompletion has a specific purpose: prepare the route and contact surfaces required by the new equipment, while removing debris that could interfere with installation. The material may include old mud or cement residue, deposits on the casing wall, fragments generated by milling, or debris released while upper well equipment is cleaned. Its …
Choosing workover fluids starts with the functions the well requires. Density must address the pressure-control objective, but the same fluid also contacts the formation, mixes with other fluids, encounters changing temperatures and may have to carry solids. A choice that satisfies only its surface density can leave important compatibility, loss and restart questions unresolved. [1, …
A straddle packer can isolate a selected part of a completion while preserving a route through the well. Whether that is a useful repair depends on the exact connection being excluded, the places where the assembly can seal and the passage left afterward. Covering a leak is only one part of the decision. The repaired …
The well productivity index puts a production rate beside the pressure drawdown required to obtain it. That makes it useful after a workover: a higher rate may reflect better inflow, but it may also reflect a lower flowing bottomhole pressure with no change in inflow capability. The comparison needs both rate and pressure, measured or …
A clear collar response can still leave a workover tool at the wrong depth. The response must belong to the intended collar on an accepted reference, and the tool’s working point may be several metres away from the sensor. A casing collar locator supports depth correlation; the completed calculation must carry that reference to the …
Oil well swabbing deliberately removes liquid from the production tubing to reduce the liquid column opposing formation inflow. A wireline-carried cup assembly lifts liquid toward the surface, and the resulting pressure change may help a completed well start flowing. Recovering liquid, observing formation inflow and demonstrating sustained production are three different findings. [1, p. 449] …
Water coning in oil wells occurs when production drawdown draws underlying water upward toward the producing interval. The resulting water production may justify a change in how the well is operated or completed, but it does not automatically identify a repairable defect. A workover acts on a particular completion or flow path; coning develops within …
A velocity string gives produced gas a smaller passage through which to carry liquid. That can help a loaded gas well, but the smaller passage also adds friction. The useful question is therefore whether the completed well can deliver enough gas through the proposed conduit to transport its liquids under the conditions expected after installation. …