Well Integrity Analysis in Gulf of Mexico Wells Using Passive Ultrasonic Leak Detection Method

Abstract

Well integrity management presents a wide variety of challenges for the industry today. With aging fields and more complex completion techniques coming into play, more efficient methods of well diagnostics and remediation are demanded. In the GOM, 45% of the wells have sustained casing pressure; therefore, the importance of having a resource that can provide an effective, accurate method of leak detection is abundantly clear. Typical methods of leak detection today include the use of spinners, temperature tools and noise logs. Mechanical means such as calipers and isolation packers are also employed. While effective for larger leaks, these methods can produce nebulous results with smaller leaks and can be time consuming. The frequency spectrum a leak produces is a function of differential pressure, leak magnitude, and leak geometry. These properties determine whether the frequency is audible, ultrasonic, or both. Typically, smaller volume leaks with a relatively high differential pressure will generate an ultrasonic signal. Based on this premise, an ultrasonic logging tool was developed and proven that detects frequency spectrums typically produced by leaks. The tool has a series of band pass filters which remove virtually all audible noise associated with tool movement, allowing continuous logging. Because ultrasonic energy will pass through compressed gas and steel, the tool can detect leaks in secondary barriers as well. Further, as ultrasonic energy attenuates quickly, the tool locates leaks with a high degree of accuracy. Using this tool, leaks as small as 0.005 gpm have been quickly located with an accuracy of a foot or less. This paper will describe a down-hole ultrasonic leak detection tool and provide case histories of where the ultrasonic leak detection tool was used to find leaks that other methods were unable to locate. A comparison of the results from conventional leak detection methods will be discussed as well.

Increased stray gas abundance in a subset of drinking water wells near Marcellus shale gas extraction

“…The two simplest explanations for the higher dissolved gas concentrations that we observed in drinking water are (i) faulty or inadequate steel casings, which are designed to keep the gas and any water inside the well from leaking into the environment, and (ii) imperfections in the cement sealing of the annulus or gaps between casings and rock that keep fluids from moving up the outside of the well (4,(40)(41)(42). In 2010, the Pennsylvania Department of Environmental Protection (DEP) issued 90 violations for faulty casing and cementing on 64 Marcellus shale gas wells; 119 similar violations were issued in 2011.…”

Full‐Life‐Cycle Analysis of Cement Sheath Integrity

“…Analysis in this study is based on a deep well (vertical depth 6300 m) in Tarim oilfield, China. e fluid density in the casing sρ w � 1.0 g/cm 3 , and the density of cement slurry ρ c � 1.9 g/cm 3 . As the difference between the maximum and minimum horizontal in situ stress is very small (at the depth of 6300 m, σ H � 140 MPa and σ h � 134 MPa), the minimum and maximum in situ stress of the well is considered equal, with an equivalent density of 2.0 g/cm 3 .…”

“…Maintaining well integrity in the whole life of hydrocarbon recovery is a key issue adversely impacting the effective and economic production [1][2][3]. is issue becomes more severe when exploiting deep resources in recent decades.…”

“…In this stage, the casing, cement sheath, and formation undertake compressive stress, among which the maximum is the tangential stress within the casing mainly due to the high sti ness of the casing. Figure 3 shows the stress state of the CSF system if the equivalent density of in situ stress is taken as 1.5 g/cm 3 . Comparing Figures 2 and 3, we can nd that with di erent in situ stress, only the stress state of the formation is di erent, while the stress state of the cement and casing is the same.…”

Wellhead based time domain reflectometry for casing integrity investigation

“…The complexity of geology, geochemistry, and geomechanical conditions in the subsurface brings great challenges to wellbore integrity monitoring. Current technologies have been mostly downhole logging methods, such as wireline based ultrasonic logging (Johns et al, 2009(Johns et al, , 2011, fiber optics sensing (Schultz et al, 2002;Cannon et al, 2013;Boone et al, 2014), electromagnetic sensing (Hawkes and Gardner, 2013), and mechanical approach (Carey et al, 2010;Carey, 2013). While these tools can provide high-resolution information of borehole conditions, they are intrusive regarding borehole occupancy and interruption to the normal operation of the wells.…”