Yaqut -1 well is located in Safed Koh Lease of Dewan Petroleum Pvt Ltd. The well was a Re-entry Well. Original well was drilled in 1984 and was classified as dry well. Dewan Petoleum decided to re-enter the same well and drill down 1356m of 6" hole to test the potential of Chiltan limestone as primary target and Sembar and Lower Goru sands as secondary targets. The Well is located in tectonically stressed/ active area with fractured formations with under-hydrostatic head. This is the cause of severe losses even at Normal Hydrostatic head. The same case happened also with offset well drilled to same depth. Cementation of liner/ casing was very poor which generated many operational issues in post-completion life of the well. Keeping this in mind, we worked on different options of slurry design, mechanical barication i.e use of External Casing Packers, Expandable Rubber Sleeves etc and multistage cementation. The geometry of 6" hole of about 1356m long interval and 5" Liner length of 2278m, did allowed only to manipulate with Slurry weights and discarded all other options. The final option of 7.9ppg Slurry was finalized after authentic Lab test results and ensuring slurry properties. Designed slurry was pumped with only 28bbl loss out of 140bbls. The USIT Log was carried out which showed best cementation results. This paper will discuss in detail the comparison of cementation results of Yaqoot-1 well with offsets. Detailed discussion of slurry designs considered for subject well along with application in under-hydrostatic fractured formations. Lab results of slurry design and USIT Logs have also been discussed in this paper to conclude the strategical justification Ultra Light Slurry Design.
Yaqut -1 well (Afiband) is located in Safedkoh Block of Dewan Petroleum Pvt Ltd at about 20km WSW of Taunsa City, district D.G. Khan- Pakistan. Well was originally drilled in 1986. Well was drilled to 2020m, tested and was declared as Dry. Dewan Petroleum, on the basis of seismic data, Re-entered the existing borehole and deepen the same to explore the targets as Lower Cretaceous (Sand Bodies), Lower Cretaceous Sand and Jurassic Limestone. There were big challenges to face before making well usable for evaluation and testing purposes. These challenges included Installation of Wellhead, drilling of cement plugs and cement squeezing of 307m (Selective) perforations in total 792m zone against four different horizons, Drilling of 1356m of 6” hole, conducting wireline logs, running in 5” Liner and successfully cementing it against loss zones. Another challenge was of severe losses because of under-hydrostatic pore-pressure regime/ profile. Detailed evaluation of cement slurry designs of offset wells, where there was poor cementation history; a long debate was opened between well services companies. Discussion included nine possible options, and on the basis of SWOT Analysis one with “Ultra- Light” cement slurry was selected. This paper discusses in detail the strategy of Installing wellhead, Drilling cement plugs & squeezing-off long interval of perforations and their pressure test, along with strategy of overcoming drilling challenges, Centralization of Liner and landing the same successfully and discussion of different 5” Liner Cement Slurry design options. Furthermore it will show lab results, subsequent study results and will outline different steps used in carrying out the design, the execution and evaluation of the results of successful operations, which resulted in a restoration of high productivity.
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