High annulus pressure in old producing wells in offshore Malaysia has become a serious issue when it reaches a limit that breaches a well’s integrity pressure envelope. According to the outlined criteria in the Operator Well Risk Management 3.0 (WRM), the operator will perform lubrication work using heavy brine. This action will temporarily reduce the annulus pressure but soon the annulus pressure will start to build up to the original threshold limit hence rendering lubrication using brine a failure, requiring operator to raise Management of Change (MOC) to keep well flowing with numerous action items needed to be in place while looking for the proper solution. Currently the usage of epoxy resin technology for leak repairs has become a regular practice in the industry. The idea of squeezing resin to seal off the micro-annulus leaks in well casing cemented annuli has become widely accepted in leak repairs. This integrity barrier entails placing and squeezing special epoxy resin into the annuli, filling up the void inside the sealed annuli and squeezing adequate volume of resin gels into the cement micro annuli. Placement of the resin gels can be difficult to execute due to the micro size path; therefore, high pressure is needed to be applied and maintained during pumping. Since 2016, the operator has had experiences in treating annulus leaks using lubrication methods and also the current deployment of epoxy resin in filling up voids and micro annulus which has enabled the operator to standardize the method to ensure high success. Surveillance logging data was utilised to determine the source of pressure and to estimate the maximum squeeze pressure to be applied during the treatment. Six wells were pilot tested and treated with this special epoxy resin squeeze, with four wells showing a complete seal while the other two wells have shown gradual pressure build up. This paper outlines the laboratory verification works on the resin mixtures to adapt to the field application in sealing the leaking annuli and describes all the six pilot tested wells that were carried out in one of offshore fields in Malaysia. The various considerations during the design of the rectification treatments as well as the experiences and lesson learnt during the execution phase are also highlighted.
Gas leak at surface wellhead equipment can contribute to a major incident if not contain immediately. High intervention cost and long lead time for wellhead replacement then required operator to find fast fit for purposes solution to avoid extended loss of production time if well idle due to integrity issue. The approach was to diagnose and quantify presence of the leak, leak communication path and leak severity by performing positive and negative test at all hanger seal port. Two method of gas imaging detection utilizing Optical Gas Imaging (OGI) and Thermal Imaging (TI) was tested to investigate the leak at gap between casing conductor and wellhead landing support ring. Preliminary study on wellhead completion schematic conclude to have two possible leak paths from 36" conductor annulus; through bottom seal 13 3/8" casing hanger or 13 3/8" annulus through casing hanger top seal. The rectification approach was to treat the leak inside out by injecting proprietary sealant into casing hanger seal to regain sealing capabilities. High performance fiberglass wraps plus metal repair putty applied as second barrier which usually use for pipeline integrity restoration. Baseline diagnostic and post treatment data was compared to evaluate the treatment performance. Out of 12 casing hanger seal port, 9 port was treated with Pressure Activated Sealant (PAS) and 3 port was treated with Time Activated Sealant (TAS) passing the acceptance criteria well barrier envelope. Proper sealant selection was crucial to treat different leak characteristic and correct injection method was important based on sealant activation mechanism. Ultimately, both gap at conductor was encapsulated using wrap system sealed the leak from outside and passed the soapy test. Thermal imaging for gas detection was not as conclusive as optical gas imaging, however most importantly both of conductor observed to have no leak at the surface. This paper outline sealant selection type and its activation mechanism used for conductor leak rectification field application. The various consideration during engineering study, diagnostic activities and rectification procedure were highlighted as well as the experiences and lesson learnt during the execution phase.
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