Application of Noise and High Precision Temperature Logging Technology to Detect Tubing Leak in an Oil Well - A Case Study

Abstract

Leak in well bore tubulars & packers leads to communication between tubing/casing or Short/Long strings thus causing enormous production losses in Oil & Gas industry. Moreover, it can cause cross flow between different reservoirs. Sometimes leak may lead to charging of shallow formations thus posing a big threat to well integrity. The detection of the source of communication presents a big challenge to the industry. Knowing the precise location of a leak helps in designing an effective remedial action thus reducing downtime and repair costs. When a fluid leaks, it moves from the high-pressure side through the leak point to the low-pressure side, where it expands rapidly and produces a turbulent flow creating noise and temperature changes. Conventional noise and temperature tools are not capable of detecting the leak point with high confidence. However, the new generation Noise and Temperature logging tools have been able to locate such leaks precisely. This paper presents successful use of Spectral Noise Logging in combination with High Precision Temperature logging (HPT-SNL) in a dual-completion oil well in Kuwait Oil Company for identifying communication between the long and the short tubing strings. The acoustic tool contains a new-generation, high-sensitivity hydrophone – a piezo crystal element that records noise in a wide frequency range (0.1 – 60 kHz). Temperature tool utilizes a super-sensitive platinum sensor with a response time of less than one second. Leak was detected at the bottom blast joint of the long string that was causing water entry into the short string thus killing the well. The technology can be used in critical oil and gas wells to identify tubing and casing leaks and address well integrity issues. It can also be used in water injection wells to identify the zones of water intake.

Measurement of wellbore leakage in high‐pressure gas well based on the multiple physical signals and history data: Method, technology, and application

“…The wellbore noise is induced by fluid flow and its spectrum is related to the size of the leakage hole, fluid properties, pressure, temperature, and flow rate 55 . Therefore, the source of noise can be identified by the spectrum characteristics, as follows.…”

“…In some situations, this noise can be masked by normal wellbore flow with similar frequency and amplitude, so it needs to be compared, identified, and analyzed. Noise generated by leakage in the cement sheath behind the casing. The fluid would flow through the cement sheath when the cement sheath loses its sealed integrity, which may be fractures 54 or microannuli 55 . Such flow has obvious starting and ending, so the noise also have clear boundaries in the wellbore longitudinal direction, which displays as as a narrow vertical strip. Noise of reservoir flow.…”

“…Noise generated by leakage in the cement sheath behind the casing. The fluid would flow through the cement sheath when the cement sheath loses its sealed integrity, which may be fractures 54 or microannuli 55 . Such flow has obvious starting and ending, so the noise also have clear boundaries in the wellbore longitudinal direction, which displays as as a narrow vertical strip.…”