Exploration activities in the state of Kuwait have been focused on the search for high quality oil from the Jurassic formations and gas in the Triassic/Permian series. The wells drilled to these prospects are very challenging because of HPHT conditions, large casing sizes, oil base mud, presence of high levels H2S/CO2 and narrow pore/fracture pressure window. As such, the cementing of the deep strings in these wells has been extremely challenging. Over the last eight years a concentrated effort has been made to introduce new technologies and materials to improve the cementing practices both from operational and safety aspects.
In 2003 the success ratio for deep cementations was highly variable. KOC along with one of their cementing service providers worked on a series of changes to practices and materials with the aim of improving job quality with high repeatability. This was based primarily on the technologies being developed in HPHT wells around the globe and especially in the North Sea and it resulted in a notable improvement in cementing performance.
Technologies and practices that had been developed include spacer technology, application of synthetic retarders, fluid loss and anti-gas migration additive improvements, development of fine grained weighting additives, use of HPHT rheometers, systematic product control, minimizing handling and safer mixing practices at the well site.
This paper will discuss the application of these technologies, materials and practices over an eight year period as a case history to illustrate the improvements made in achieving consistent cement quality and final slurry placement for the deep casing and liner strings and will conclude with recommendations and lessons learnt during this process.