Abstract
Current surface gas detection technologies are flawed in that they are limited in speed or can only detect certain gas types. Current gas detector technology does not provide a complete view of reservoir conditions without additional and costly inferred measurements from logging while drilling (LWD) or wireline tools. To overcome these limitations, a new instrument and methodology have been adapted from the chemical process industry and developed for drilling applications.
The initial goal was to develop a gas detection system capable of quantitatively analyzing more than 20 chemical species in less than 15 seconds. Several gas analyzers were reviewed for ruggedness, speed, accuracy, and chemical species detected. The system had to be capable of withstanding shipment to the rigsite and rigsite conditions. In addition, the system needed to be operable remotely to reduce personnel at the site. A gas chromatograph flame ionization detector (GC-FID) was used as the benchmark for accuracy and response.
A quadrupole mass spectrometer that would jump from mass peak to mass peak was selected. This spectrometer is characterized by an accuracy rate within 0.1%, a faster response time than a GC-FID, and the ability to analyze 32 chemical species in less than 10 seconds with drift less than 0.1%. The system was the best match to meet the initial goal. Developing a quantitative mass spectrometer proved to be a greater challenge. This objective was achieved by determining the chemical species fragmentation patterns and sensitivities at the base before deploying the system to the rigsite, where only a verification gas blend was necessary. The system can replace slower, qualitative mass spectrometers at the rigsite at a reduced cost with 10 times the data density.
The initial goal of developing a system capable of analyzing more than 20 chemical species in less than 15 seconds was achieved. Additionally, adapting instrumentation and methodology from the chemical process industry to drilling applications led to the development of a fully quantitative mass spectrometer at the rigsite with cycle times of less than 10 seconds for 32 chemical species.
