Shaft gas cut early-stage active monitoring method based on low-frequency elastic wave response characteristic

Abstract

The invention discloses a shaft gas cut early-stage active monitoring method based on a low-frequency elastic wave response characteristic. By adopting the method, the gas containing rate of an annulus nearby the upper portion of a drill bit can be monitored the drilling process in real time, gas cut can be found as early as possible, timely warning can be given, monitoring is sensitive and reliable, precious time can be won for ground design and well control operation implementation, and the safety of an oil gas drilling project can be guaranteed. In the drilling process, a drilling fluid flows through an underground monitoring short section through the annulus, the underground monitoring short section transmits pulse signals according to fixed frequency and converts received response signals into electric signals, two attribute values including first arrival time and a peak value of each of head waves of the electric signals are extracted for encoding, whether gas cut occurs or not is judged, if it is determined that the gas cut occurs, gas cut information is sent to a ground control center through an underground wireless signal transmitter.

Description

technical field [0001] The invention relates to a monitoring method, in particular to an early active monitoring method for wellbore gas invasion based on low-frequency elastic wave response characteristics. It belongs to the technical field of analysis and measurement control. Background technique [0002] In order to meet the needs of the national energy strategy, oil and gas drilling technology continues to develop. Currently, oil and gas drilling is developing towards deeper formations and deep ocean waters. Gas kick refers to the entry of formation gas into the wellbore annulus due to pressure difference or substitution, which is a common drilling complication. If gas intrusion is not handled properly, it will further develop into wellhead overflow, or even blowout accident, resulting in major production safety accidents. At present, gas intrusion monitoring is mainly carried out on the ground or near the wellhead, such as the monitoring of fluid volume changes in dri...

AI Technical Summary

Problems solved by technology

The sound wave propagation path of this technical solution is long, the received signal energy attenuation is significant, and there is more noise interference, especially in the early stage of gas invasion with low gas content, the abnormal response characteristics of sound waves are often covered by noise, and the sensitivity and reliability of monitoring Poor sex

Theoretically, the change of sound wave propagation characteristics is very beneficial to the early monitoring of gas intrusion, but it is still not perfect at present. The difficulty lies in minimizing the attenuation effect and identifying characteristic signals

Images