Abstract
The intention of this paper is to discuss and recommend effective production logging techniques for low rate horizontal gas wells. Between June 2005 and September 2006, a total of eight wells were evaluated using either traditional production logging (PL) tools or downhole video logging tools. Pressure, temperature, nuclear fluid density, single capacitance, capacitance array, fullbore spinner, caliper, and gamma-ray data were retrieved by production logging methods. Video logging collected thousands of wellbore images as well as pressure and temperature information.
A significant issue in logging horizontal wells is the method of delivering tools into the well. Tubing diameter, open hole diameter, horizontal length, horizontal trajectory and the desired results all influence the selection of conveyance method. The methods used in this study were CoRod, coiled tubing (CT) and wireline tractor.
The production logging data indicated liquid accumulations however the different logging tools showed varying degrees of detail. As an example, the capacitance array tool tended to show liquid with gas pockets while the radioactive density tool and spinner tool indicated 100% liquid. Video logging data provided definitive images of gas bubbles and slugs flowing through liquid.
The objectives of a logging program will dictate either a qualitative or quantitative evaluation. Video logging is an excellent technique to use as a general overview when initially investigating openhole sections. It can provide insight on complex production problems that never would be suspected or detected using traditional production logging methods.
