Production logging

While most types of logs are used to characterize the wellbore, formation, and fluids prior to well completion, a number of logging tools are available to provide information during production operations and beyond. This article discusses the various types of production logs and how they can often be used together to provide crucial information for understanding and resolving problems..

Production logging

Production Logging is one of a number of cased hole services that includes cement monitoring, corrosion monitoring, monitoring of formation fluid contacts (and saturations), perforating and plug and packer setting. Services performed in dead, overbalanced, conditions can use relatively simple surface pressure control equipment and are often performed using large open hole style logging cables. With a well that has pressure at surface it is normal to use a small logging cable in order to;

1.     Minimise the tool weight needed to overcome the well pressure trying to extrude the cable.

2.     Minimise the grease injection requirements to seal around a wireline cable.

Wells with surface pressure typically have a completion tubing of relatively small internal diameter, ID, compared to the casing size across the reservoir. This reduced ID means that cased hole toolstrings for live wells are typically sized at 1-11/16" in order to pass through the smallest nipple in a 2-3/8" tubing. It is usual for cased hole equipment manufacturers to produce a platform of sensors with common power supplies, telemetry (or memory) to cover production logging, saturation logging, and multifinger caliper corrosion logging.