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Abstract Most cementing simulators do not account for lost circulation events or the compression/expansion behavior of non-aqueous fluids (NAF) during cement placement. As a result, their output can be unreliable, resulting in potentially poor recommendations and operational performance - in potentially critical well-cementing situations. When isolating potential flow zones and/or performing zonal isolation in high-temperature/high-pressure (HT/HP) and/or deepwater environments for example, accounting for lost circulation and compressibility of non-aqueous fluids can make the difference between a successful cementing operation and a very expensive failure. In addition, overall reliability compared to existing simulators is improved operationally and technically assuring the objectives of the cement placement can be met while complying with new regulations as they can apply to zonal isolation. This paper will explain the theory and methods behind the advanced cementing simulator inputs and resultant outputs with case histories demonstrating some of the field validation of the new simulator's reliability. Also, existing technology in the simulator will be highlighted summarizing the robust package available to meet the objectives of cementing job placement in light of recent industry changing events. Background To the authors' knowledge, the existing current simulator technology on the market cannot account for losses while cementing in addition to compressibility/expansion of NAFs simultaneously during cement placement. Furthermore, the authors could not determine if the market's advanced modeling software used could simultaneously handle the same events using a dynamic wellbore temperature profile or multiple cementing fluids (i.e. drilling fluids, spacers, cements) with different densities. A compositional model to define fluid densities at downhole temperatures/pressures, multiple rheology sets for varying temperatures/pressures of the various fluids, and temperature dependence of the cementing fluids for friction pressure determination on placement ECDs is essential for proper modeling. These requirements should not be confused with riserless cementing simulations where returns are planned to be lost at the sea bed or mudline, creating a " pseudo-mudline.?? Riserless cementing does not have to consider the wellbore geometries and friction pressures in the case of cement placement with the marine riser in place. |
