This paper is a case study of a well intervention performed by PETRONAS Carigali Sdn Bhd (PCSB) in Sarawak region to investigate and rectify a breach in well integrity. The review and discussion demonstrate that the intervention not only ensured compliance with existing well bore risk management guidelines but also reduced operational rig cost and enabled increase in production. The paper identifies the aspects of what appears on first view to be a straightforward well integrity diagnostic process, but which on deeper evaluation exposes the wider and acute impact of the outcomes of such a diagnosis. The nature of the diagnostic technique is examined, and the interrelated impact on PCSB HSE requirements, platform operating efficiency, and field-wide production. The well intervention and the subsequent targeted rectification made possible by the precise nature of the diagnosis, enabled PCSB to bring this well back online and restore its gas production. This gas production is vital for several of the gas lifted wells in the field. Restoration enabled PCSB to increase field production significantly. The study concludes that accurate, reliable and rapid integrity diagnostics should not be evaluated as only relevant as a means of HSE management but also a means of cost management and in sustaining or increasing overall production.

Sand production in oil and gas wells not only poses a serious threat to hydrocarbon production, but can also cause extensive damage to equipment, such as subsurface tubing, surface valves and pipelines. Produced sand is also an environmental hazard, and needs to be disposed of in an environmentally safe way. Effective sand management is therefore a major concern in the oil and gas industry.The key challenge is to optimize hydrocarbon production by minimizing the production of sand and in doing so reduce the damage caused to well completions and surface equipment. On a sand-prone well, this is typically done by identifying a maximum sand free rate (MSFR), and then limiting production to this level. Conventional sand detection methods rely on surface measurements. However, these methods do not provide a complete picture of the sand production down hole. To gain a more comprehensive understanding of the problem, sand needs to be detected at its point of entry into the well bore. In this way, the best remedial treatment can be designed.To answer this requirement, an ultrasonic sand detection tool has been developed. The tool detects ultrasound energy generated by sand grains as they enter the well bore and strike the tool in a radial manner. Sand moving parallel to the well bore axis is not detected, thus the tool can indicate the exact entry point of sand, anywhere along the producing interval. The operator can then specify the most appropriate and cost effective remedial action, such as installing sand screens or applying chemical treatments. By employing such a tool, the cost of remedial action can be minimized and hydrocarbon rates can be optimized to achieve sand-free production. The tool can also be used to evaluate the performance of sand screens and other control devices, and if run in tandem with production logging tools, can monitor sand production in conjunction with well performance. This paper presents the results of a case study where a downhole ultrasonic sand detector was used to monitor sand production in five gas-producing wells from the Northern Malay Basin. The methods behind this "sand survey" are presented, along with a description of the tool.