This paper details the deployment of Spectral Noise logging confirming barriers in a complex abandonment of an onshore field in the Netherlands to fulfil regulatory requirements and to support sustainable abandonment. After initial plug and abandonment (P&A) activities on the main reservoirs, measurements showed pressure build up inside annuli. Spectral noise, high precision temperature and production logging were performed to determine the cause of sustained annulus pressure (SAP) and the location of leaks. The data acquisition was performed both under shut-in and pressure bleed-off conditions and both log responses were compared to identify changes in noise patterns. The noise from specific events such as channelling or reservoir activity was detected, so the abandonment program could remediate these issues successfully. Application of spectral noise logging in this field yielded evidence that this technology can identify annulus flow for very minor build-up rates (0.1 bar/day). This paper further demonstrates the ability to allocate the SAP source behind multiple barriers and to validate plug integrity. It was observed that noise responses have a good correlation with ultrasonic cement evaluation logs aiding better understanding of the gas migration mechanism and change in noise patterns. The temperature logging in most of the wells did not indicate any difference between shut-in and bleed-off regimes due to the very low leak rates. However, it did demonstrate the absence of any major cross-flow between formations. Insights in behind-casing flow geometry along the borehole helped to work out a remedial strategy to proceed with a sustainable abandonment of the logged wells. For specific and complex cases, where conventional pressure monitoring and pressure test techniques cannot provide conclusive results, the spectral noise logging technology becomes a useful differentiator in selecting between possible scenarios during execution, The technology therefore brings significant value by reducing project cost without compromising the quality of the abandonment.
When producing aerosol-based preparations, the quality of aerosol packing (AP) is determined mainly from the results of testing the hermetic sealing.The control of the latter by the bubble method in a hot water bath does not meet the present industrial requirements as the aqueous medium causes active corrosion of the AP body while the test consumes much power, and control is subjective.The Dzerzhinsk branch of Nizhegorodsk Polytechnical Institute designed automated system AKG-Gs for testing valve airtightness in seamless AP. The sensitive element of halogen leak detector GTI-6 was used as a gauge for detecting the gas-phase leak from the AP. The possibility and advantage of using such a gauge was examined in [i-3].Considering the fire and explosion hazard of the industry, the gauge is made with an explosion-proof shell, is hazard-free, and ranked IExdPVT4 safety class [4]. The measuring block together with the gauge is set up outside the hazardous building.In view of the possible loss of gauge sensitiveness, control is effected in two stages: in the first stage, APs with large leakages are detected and discarded and, in the second, testing is done to the required sensitiveness level.Correspondingly, the device consists of two blocks: a block with low control sensitiveness set up directly on the conveyor and a highly sensitive block with a rotor-type module having eight platforms.Control at each stage is effected by two gauges operating alternately.The gauges in the sensitive second block are activated after detecting and discarding defective ones in the first block.A jet of clean air is blown onto the low-sensitive block to restore the sensitiveness of the idle gauge.To reduce the fluctuations of background signal and restore the sensitiveness of the gauge rapidly after contact with the coolant leaking from defective APs, the electrical circuit of the leak detector has a follow-up system that suppresses slow deviations of background signal from the zero line by controlling the filament current of the sensitive element.Threshold values of background signal variations causing filament current fluctuations are controlled.In view of atmospheric contamination of the building with the coolant, the sensitive elements in the second block are partly isolated from the ambient environment by a shell of organic glass under which clean air is blown at a slight excess pressure. Figure 1 shows the layout of the equipment.APs 1 on conveyor 7 enter the low-sensitive block 2. In case of rejection, the output signal of leak detector GTI is compared with the given value by the liminal device LD and, when in excess, is transformed into a pneumatic signal in eiectropneumatic converter (PC) and reaches pneumatic cylinder 3. The rejected ones are automatically dumped into bunker 4 by pneumatic cylinder 3. The control sensitiveness at this stage is 0.5 m3"Pa/secoGood ones continue to move on the conveyor to highsensitive block 5 where they are held by sprocket 8 and, holding on to turnstiles block 9, travel to position I on rotor 6. As t...
Failure of the primary barrier in most cases results in observable sustained annulus pressure. For other such cases, sustained annulus pressure may not result, and leak associated fluid movement remains confined to deeper intervals, for example as cross flows. This manuscript introduces a comprehensive approach to assess the current status of primary and secondary barriers and, for this case of integrity loss, to quantify the downhole leaks rates. The assessment includes: Determining individual pipe wall thickness of first two concentric metal barriers using electromagnetic pulse logging techniqueSpectral Noise Logging to locate the active leaks and to verify the sealing integrity of cement barriersHigh Precision Temperature logging for downhole leak rate quantification utilizing temperature modeling The paper contains the physics of measurement, lab and field tests of the barrier assessment technologies, followed with a case study: A single string gas producer, with sustained A-annulus pressure. Additional survey findings allowed the identification and quantification of a crossflow resulting from leaks.
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