Disposable Wells: A Monobore One Trip Case Study.

Abstract

Abstract This paper will discuss a Monobore one trip cement through completion system.The system was designed to add artificial lift capabilities and improve safety to short life monobore wells.The disposable well bore concept is gaining popularity in regions worldwide.This paper will also discuss case histories including operation issues and problems and how they were solved. Operational procedures will be outlined to effectively demonstrate, and discuss the decision making process when determining the most cost effective candidates for this technology. Introduction Throughout the oil and gas industry focus is turning to economical methods of completing wells that in some case due to high completion cost would not be feasible.Over the years several methods have been utilized in an attempt develop adequate means to safetly and productivily complete these wells.These methods have ranged from merely cementing the tubing in place to completing in several stages so as to utilize necessary safety and gas lift equipment.A more fit for purpose completion system for disposable wellbores would include all the equipment necessary to safely and economically complete these wells.This system would also need to be a true Mono-Bore one trip completion which would allow cement to be pumped offline freeing up the rig to move to another location on the platform.Since the inception of this completion techno;ogy an average of 40 hours of rig time has been eliminated from each completion (see figure two). This reduction has represented a considerable cost saving when utilized on the entire platform. Components of this one trip mono-bore system would also need to function properly following the cementing operation.These capabilities currently exist in the Mono-Bore CemenThru completion system.This system relies on specifically designed cement tolerant components.This system is currently being used in the Gulf of Thailand. Mono-Trip CemenThru Completion System Completion Design. The Mono-Trip system is based on a true mono bore design with one trip capabilities. More importantly the system will operate as intended after cement has been pumped through each of the components.Pressure cycles are utilized throughout the completion to operate the various components. As depicted in the graphic(Completion Designs fig 1) several completion designs have been utilized for this particular type of completion philosophy. Conventional methods (fig 1) show the typical mulitizone completion technique.Although effective the cost associated with the components and the time required to complete can reduce the economics to an undesirable level. The second method Monobore (fig 1) is obviously the most economical since it consists of tubing string and a SCSSV.The drawback to this design is the absence of any ability to gas lift as he well starts to deplete.Also since a packer was not used it would not be possible to cut above the cement and run completion strig with gas lift components as there would be no positive seal to allow safe operation of gas lift. Prior to the design and implementation of the Mono-Trip system a two trip method was utilized which was time consuming adding cost to the completion of the well.The two-trip method required up to twice the amount of time to complete than the currentone-trip method.