Methodology and Approach of Lightweight Cement Evaluation in Horizontal Well for Integrity Assurance and Future Reservoir Development

摘要

Well integrity is a critical issue for oil and gas companies.The failure of a wellbore integrity can result in financial consequences,have environmental impacts,and could damage a company's reputation.Cement placement is one of the most critical components with respect to ensuring mechanical support of the casing,protection from corrosion and isolation of permeable zones.Light weight cement recipes can help to overcome lost circulation problems during drilling or cementing,however,there are challenges with respect to the applications of Cement Evaluation logs,which are used to determine the effectiveness of the cement job.This is due to the fact that light weight cement exhibits high amplitude and little alteration in the log waveform on conventional bond logs because of its lower fluid density and compressive strength.This research describes the application of an Advanced Ultrasonic Imaging Tool that combines traditional pulse-echo techniques with a new ultrasonic technique,which can differentiate low-density solids from liquids and distinguish light weight cements from contaminated cement or liquids.Furthermore,this research describes the application of the tool in a highly deviated well,which required the usage of a tractor deployed wireline operation.The results indicated low decentralization readings across the logging intervals and reflected the good data quality observed in the ultrasonic measurements.The processing flag track did not identify the presence of any errors related to the echo acquisition and data processing throughout the logged interval.Overall,a strong signal reflection was observed along the logging interval,suggesting clean inner casing surface.The combination of light weight cement logging on a tractor conveyance tools has been proven to be a successful approach.The application of this technique benefits Mubadala Petroleum Thailand with significant cost savings and reduced Health,Safety and Environment(HSE)risks for the overall operation.This paper will demonstrate the following:1.Cement bond log and evaluation of light weight cement by Advanced Ultrasonic Imaging Tool in comparison to conventional cement bond log tool.2.Job design,efficiency gains and improved well integrity assurance from the operation.3.Special cement designs intended to reduce the weight while maintaining important physical properties,i.e.compressive strength.4.Efficient downhole data acquisition methods utilizing wireline tractor logging.The material presented in the paper is based on the actual operations of Mubadala Petroleum,with examples illuminating light weight cement used in a horizontal well,as well as the combined application of an isolation tool with a wireline tractor,which is the first such application in the Gulf of Thailand.It will also show the well integrity assurance achieved,operational efficiencies gains and risk reduction obtained.