Leak Detection by Temperature and Noise Logging
- Ihab Nabil Khalil (Abu Dhabi Co. Onshore Oil Opn.) | Maxim Filenev (Kazan State University) | Arthur Aslanyan (TGT Oil and Gas Services) | Irina Aslanyan (TGT Oil & Gas Services) | Jamal Barghouti (TGT Oil Co.) | Mohamed Hassan El-Hamawi (Abu Dhabi Co. Onshore Oil Opn.) | Rasheed Ahmad Al-Hassan (Abu Dhabi Co. Onshore Oil Opn.) | Bassam Salim (Baker Hughes)
- Document ID
- Society of Petroleum Engineers
- Abu Dhabi International Petroleum Conference and Exhibition, 11-14 November , Abu Dhabi, UAE
- Publication Date
- Document Type
- Conference Paper
- 2012. Society of Petroleum Engineers
- 5.6.1 Open hole/cased hole log analysis
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Monitoring and handling Sustainable Annulus Pressure (SAP) is a daily challenge in today's oil and gas industry. Well integrity failure can affect production and the environment and, consequently, lead to high economic losses from fixing the resulting damage. Once SAP is confirmed, its source should be located and shut off as soon as possible. The biggest problem is leaks behind multiple barriers, which are not clearly seen in conventional temperature and noise logs. However, recent developments in temperature and noise logging tools and interpretive techniques have been rewarded by achieving high resolution and sensitivity enabling the detection of previously undetectable leaks. This paper describes two cases of integrity failure in the B and C annuli detected by the new integrated high-precision temperature and spectral noise logging technique, or HPT-SNL.
The HPT-SNL suite has several distinct features. Temperature is measured during down passes at low speed. Noise data are acquired at multiple stations enabling data stacking and extraction of correlated noise from the prevailing uncorrelated noise. [4, 7] The key element of the high-precision temperature logging tool is a super-sensitive fast-response temperature sensor (response time less 1 sec) that can pick up the smallest (0.003°C resolution) leak-generated perturbations of wellbore-fluid temperature through multiple barriers. 
SNL3 represents a new generation of noise tools. Its key component is the new super-sensitive hydrophone detecting noise in a wide frequency range.  The tool captures 100-60,000 Hz noise with a high-sensitivity hydrophone, which detects noise in the wellbore, casing annulus, faits, fractures and matrix. The resulting digitised acoustic wave sample consists of 1024 time bins. About 50 noise samples are stacked at each station, filtered of uncorrelated noise and processed into 128 frequency channels in the form of a colour spectrum. [2, 7] The frequency range can be adjusted as required. Conventional noise tools normally measure noise power in only three to six narrow frequency bands and fail to detect noise beyond these frequencies.
Multichannel spectral noise logging is an important improvement over conventional noise measurements; it provides high-frequency resolution to track noises within a wide frequency range in cases of leaks and cross-flows. Leaks are detected by two consecutive surveys under shut-in and bleed-off conditions. The difference in noise level between the two surveys is interpreted as caused by flow due to pressure bleeding.
Both logging tools record data in cost-effective memory mode.
Case 1: Producer OP-01
The first example illustrates the location of a gas leak in the horizontal producer OP-01. Well OP-01 was drilled in 2002 and cased with 9 5/8" casing. A failure in dropping the top plug was reported while cementing the 9 5/8?? casing. However, the plug was forced down by 100 bbls of water and 465 bbls of mud with their complete loss. A deviated 8½" section was then drilled. A 7" liner was run and cemented in order to continue with the drilling of a 6" horizontal hole.
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