Mud removal and cement placement during a cementing operation are key factors to ensuring zonal isolation. Actual well testing results show that majority of wells have zonal communication during the life of production. The communication between water and oil zones may significantly affect oil production and require expensive remedial squeeze treatments. Fully understanding the flow characteristics and interactive behaviors in mud, spacer, and cement is an important step to ensure critical zonal isolation.A newly developed computational fluid dynamics model helps end users better understand the transport phenomena of intermixing multiple fluids. Fluid decay resulting from the intermixing involving the mud, spacer, and cement systems is quantified for given downhole conditions of wellbore geometry, fluid properties, pump rates and casing centralization. The robust method allows the analysis of potential hydrocarbon production zonal isolation success and optimization of cement placement. This advanced fluid displacement simulator has been field verified with impressive results for a wide range of annuli. A recently developed pseudo 3-D visualization module aids in understanding the complex phenomena as well.Some field cases used for verification are included. The detailed job analysis demonstrates the methodology used to study the effects of fluid systems, pump rates, and centralization configurations and provides application engineers the opportunity to understand different scenarios while optimizing key parameters to achieve top tier results.

The National Energy Technology Laboratory (NETL) in conjunction with industry partners began a project to assess field-generated foamed cement at pressurized surface conditions. The collected samples were compared to previous field-generated samples as well as equivalent samples generated with current laboratory protocols following the recommended practices in American Petroleum Institute's Recommended Practice (API RP) 10B-4; atmospherically generated. In-situ samples of foamed cement were successfully captured in constant pressure (CP) cylinders under field conditions and analyzed while under pressure using multi-scale computed tomography (CT) scanning. The comparison of laboratory and field samples addresses changes to the cement under in situ conditions. Initial results highlight key differences in laboratory and field-generated foamed cements. Results of laboratory testing indicate a correlation between bubble size distribution, permeability, and strength. Field-generated samples show changes in pressure significantly influence the bubble size, while the flow of the slurry into the pressure cylinders created less homogeneous cured foamed cement. This paper discusses further research of in-situ field generated foamed cement behavior. These data provides insight to support the ongoing effort to help predict a method to correlate testing for foamed cement performance in the laboratory that would compare to more representative field behaviors.

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.

The risk of improper temperature selection for the design and testing of cement slurries can be detrimental to well construction operations and could affect a well's integrity. The methods for temperature selection in API 10B-2 do not consistently reflect the representative bottomhole conditions for high temperature applications. More so, consider 10B-2 guidance valuable for proving benchmarks in the high temperature domain. Therefore, numerical temperature simulators help manage the risk by predicting the anticipated bottomhole cementing temperatures. Currently several temperature simulators are in use to predict, with better accuracy, cementing bottomhole temperatures. The manuscript investigates the strange differences in predictions between the simulators for a range of high temperature applications. The results of the work efforts should help end users understand the outputs allowing better judgement when selecting representative bottomhole cementing temperatures for a given application.

Drilling exploration wells can present challenges to well delivery with the more notable including unpredictable formation (in-situ) pressures. The unpredictable pressures, such as wells experiencing high background gases while drilling the openhole, place more emphasis on the ability to provide isolation successfully to ensure well integrity. In addition, the unpredictable pressures can affect the casing design as well as the wellbore stability, which can have logistical restraints associated with a remote location's response time. As a result, a method or series of practices led to cementing success providing the isolation required to ensure well integrity and deliver the well objectives safely.