SUCCESSFUL APPLICATION OF SINGLE STAGE CEMENTING WITH FIBERED CEMENT SLURRY IN LOW-FRACTURE-PRESSURE PRODUCTION FORMATION - A CASE HISTORY IN INDONESIA

摘要

Sanga-sanga field in Kalimantan, Indonesia is a development field which is characterized by highly fractured formation with low fracture gradients. As a result of the formation characteristic, lost circulation has been challenging issue during drilling and cementing the well to achieve zonal isolation. Lost circulation issue was excessively severe in the production section of the Sanga-Sanga field. The losses during cementing on some wells resulted in uncemented annulus and poor cement to casing bond at the target depth of the production casing sections. The consequences of the losses during cementing were Sustained Casing Pressure and gas kick after pay zone was perforated. Additional work including top jobs to bring top of cement to surface and squeeze jobs to repair undesired cement bond quality were common practices in this field. This remedial treatment reduced the rig efficiency, added the drilling cost, and delayed the production plan. Now more so than ever with the oil and gas industry in a downward slide, it is critical to combat the lost circulation issue and improve efficiency. A new slurry system was designed and introduced to combat lost circulation during cementing operations. Optimized 1.4 SG low density slurry with engineered fiber was successfully used to cement 12 1/4-in × 9 5/8-in. production section. A cement blend with low density hollow cenosphere in optimum ratio was tailored to for mechanical properties of low density slurry that would develop high compressive strength to meet the perforation requirement. As a complete package to manage lost circulation, engineered inert fiber was added to the slurry to bridge the fractures and prevent lost circulation. The engineering changes to the cement slurry resulted in the cementing jobs performed without lost circulation, excellent cement bond quality, and pay zone was perforated without any issue. This paper presents case histories study of several wells and laboratory designs in which the optimized light weight slurry and engineered fibers that successfully treated losses encountered during cementing operations.