ClampOn (Norway)

Abstract Acoustic Sand Detectors (ASDs) have been widely used on topsides and subsea flowlines to measure sand production for the last 25 years. Essentially, ASDs are filtered microphones, strapped onto a bend or tee, that detect ultrasonic noise generated by impacting sand. ASDs are typically used either to detect the presence of sand or to quantify the sand rate. In the former case the well will typically be choked back when sand is present. This approach has the disadvantage that production may be curtailed even when sand production is too low to be problematic. Alternatively, the ASD could be calibrated by means of a sand injection. Once calibrated the ASD can output the sand rate in grams per second, allowing the operator to judge whether the sand rate justifies choking back the well. This strategy can significantly boost production rates. However, sand injection is not always feasible for topsides ASD installations and has never been done subsea (to our knowledge). This paper summarises work that attempts to address this limitation. A correlation was developed that calculates ASD calibration coefficients without the requirement to perform a sand injection. It works on the assumption that sand noise increases when fluid noise increases, with additional corrections for various multiphase flow effects. The correlation was developed using historical data from laboratory tests and from offshore sand injections. It was then validated against additional historical topsides injection data from platforms in the North Sea. In this initial assessment the correlation was validated against approximately 800 data points. One of the main potential applications of the correlation is to help estimate sand rates using data from subsea ASDs. Unfortunately, no suitable subsea data was available that could confirm the validity of the correlation, but it was shown that ASDs respond differently when installed subsea. Subsequently, laboratory flow loop testing was performed with ASDs installed on a pipe submerged in a pool. This confirmed that the correlation has a similar accuracy for both topsides and subsea ASD installations. The correlation is currently being trialed by an operator with a view to using it as a tool within their overall sand management strategy. ASDs are widely installed, but their output is often poorly understood or misused. This paper outlines the correlation methodology and identifies the possibilities and limitations of other approaches. The validation and testing exercises also flag a range of other issues when using ASDs; the effects of poor installation; how subsea acoustic attenuation affects ASDs; and important considerations when performing sand injection calibrations.

Abstract Tomographic methods are used with ultrasonic guided wave wall thickness monitors to provide two-dimensional maps of the wall thickness throughout a monitored area. Tomographic monitoring systems are typically configured with 16 to 32 non-intrusive ultrasound transducers positioned in predetermined patterns for optimal coverage and resolution. Other monitoring systems have much fewer transducers, positioned according to the pipe geometry and wall area of main concern. Although these systems are not optimized for wall thickness mapping, the same or similar tomographic methods can improve analysis and interpretation of the datasets they produce. Algorithms are sought for implementation in responsive, interactive software for browsing and analysis of recorded wall thickness monitoring data. Simple tomographic algorithms are also desirable for use in embedded software. A "light weight" tomographic algorithm is outlined, and a prototype implementation is tested against a proven full-scale tomography software package. The two approaches produce similar results on small datasets corresponding to wall thickness monitoring systems with few transducers installed. For the larger datasets generated for high resolution wall thickness mapping, the reference software is superior in terms of both computational load and accuracy.

Abstract The ClampOn DSP Well Collision Detector is a real time ultrasonic monitoring system for detection of a drill bit in the proximity of existing wells. The system provides real time data during drilling and thus supplements collision risk analyses and positioning data. The monitoring system lends from ClampOn's well-proven series of ultrasound sensors for sand monitoring, PIG detection, and leak detection. The working principle of the Well Collision Detector is discussed briefly. An application example from a drilling operation is shown to illustrate the utility of the system.

Abstract Corrosion and erosion detection and monitoring are essential prognostic means of preserving material integrity and reducing the life-cycle cost of industrial infrastructure, ships, aircraft, ground vehicles, pipelines, oil installations, etc. Spatially dynamic pipeline monitoring systems have to necessarily face extremely hostile conditions of operation including surface roughness, fluid loading issues, temperature variations, and a host of other factors that make development of a robust wall thickness assessment tool a challenging task. This paper describes the working of ClampOn's Corrosion-Erosion Monitor (CEM) - an online, real-time path based thickness assessment tool that deploys a set of transducers over a given pipe area, and utilizes a combination of resonance and dispersion based principles to assess wall thickness loss. This instrument was developed keeping the needs of the oil, gas and petrochemical industry in mind, both upstream and downstream, but because it essentially monitors reductions in wall loss, it can find applications in many other industries. Experimental and analytical work in- house provide very promising results pertaining to the functionality of the CEM system, and some of these results have been discussed in this paper. The CEM is a permanent installation on the outer pipe wall to produce real-time pipe wall thickness information, not as a spot measurement, but as a unique average path wall thickness. This state-of-the-art technology is extremely versatile, and can serve as a particle and sand monitor as well.