Spinner Logs in Oil Wells: From Spinner Response to a Flow Profile

A spinner log records the response of a rotating impeller to fluid moving past it. Turning that response into an interval contribution requires more than reading revolutions per second from a track. The interpretation must account for tool motion, calibration, the velocity distribution across the flow passage and, where several phases coexist, how those phases …

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Pulsed Neutron Logging: Is There Movable Pay Behind Casing?

Pulsed neutron logging can help identify hydrocarbons remaining in a formation behind casing. It does not, by itself, establish that those hydrocarbons will move into the well at a useful rate. A saturation interpretation describes pore occupancy; producibility also depends on connected flow paths, fluid behavior and reservoir pressure. That distinction should remain visible from …

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Multifinger Caliper Logs: What Internal Metal Loss Looks Like

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, …

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Wellbore Cleanout Before Recompletion: Where Does the Debris Come From?

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 …

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Choosing a Workover Fluid: Brine Density, Compatibility and Formation Damage

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, …

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