Innovative and Unconventional Approach to Cementing A Ballooning Well Leading to Good Zonal Isolation

Abstract Good cement bond log and sufficient zonal isolation are important aspects of production wells. Proper cement design and displacement are essential to ensure the cement objectives are met. Well A is one of four development wells, located in East Malaysia. The well was a gas producer, therefore good zonal isolation at the gas intervals are of paramount importance. Coupled with high inclination and formation with narrow pore pressure and fracture pressure margin, ballooning condition was encountered while drilling the reservoir section. These challenging conditions push the boundary of conventional cementing design further to implementation of unique and novel cementing approach to ensure no losses, minimal mud contamination with cement slurry and ultimately produce good zonal isolation. This unexpected conditions of the well lead to re-designing the cement slurry and revamping the placement procedure for the 7" liner across production zone. Operator’s limited experience with cementing in ballooning conditions hampered any reference which could be useful for the job design. Required formation permeability, porosity data, mud flowback volume and duration of mud flowback at static condition were carefully assessed and taken into consideration in the cementing job design and pumping program. Based on the data gathered, an unconventional cement placement technique with specialized spacer and slurry design were proposed Well A, instead of complex back-pressure application technique in order to meet all required cementing objectives. The cementing job was executed as per plan and no losses were observed during the entire cement job. Cement evaluation through cement bond logs indicated that enough isolations across the hydrocarbons zones of interest were obtained. Moreover, cement bond logs also showed good zonal isolation were also attained above and below perforation intervals showing very little contamination of mud backflow into the cement slurry. The cementing technique used proved to be relatively simpler and cheaper as it requires no additional equipment to rig up to execute compared to complex back-pressure technique which done incorrectly may lead to losses or remedial cementing. The successful cementing operation showcased that the planned cementing technique and slurry design were effective for the cementing of abnormal well conditions. This success also highlighted the importance of job pre-planning and necessity to acquire all required data prior to actual operation. The job technique and design was replicated in subsequent wells which had similar well ballooning condition and resulted in great success.