Issues With the Density and Rheology of Drilling Fluids Exposed to Extreme Temperatures and Pressures

Author(s):  
Mario Zamora ◽  
Sanjit Roy ◽  
Kenneth Slater

The 1980’s introduction of costly non-aqueous drilling fluids finally sent the industry a wake-up call to seriously acknowledge the significant impacts of temperature and pressure on the downhole density and rheological properties of drilling fluids. Despite notable progress since then, key issues remain, mostly related to inherent complexities and uncertainties associated with quantifying these effects. Some issues are technical; others are procedural. Concerns are particularly critical on wells drilled under extreme HTHP (high-temperature/high pressure) conditions, in deepwater, and in Arctic and other ultra-cold locations. The primary objective of this paper is to discuss existing issues from well-integrity and wellbore-integrity perspectives, with focus on determining hydrostatic pressures and rheological properties under downhole conditions. Also included are new representative volumetric-behavior and viscometric data measured in the laboratory under extreme HTHP conditions.

2013 ◽  
Vol 28 (03) ◽  
pp. 278-288 ◽  
Author(s):  
Mario Zamora ◽  
Sanjit Roy ◽  
Kenneth S. Slater ◽  
John C. Troncoso

Author(s):  
Qian Ding ◽  
Baojiang Sun ◽  
Zhiyuan Wang ◽  
Yonghai Gao ◽  
Yu Gao ◽  
...  

Abstract In deep-water drilling, the drilling fluid is affected by the alternating temperature field derived from the low temperature of the seawater and the high temperature of the formation. The complicated wellbore temperature and pressure environments make the prediction of rheological properties of the drilling fluid difficult. In this study, the rheological properties of water-based drilling fluid in full temperature and pressure range of deep-water conditions were tested from 2 to 150 °C (35.6 to 302 °F) and 0.1 to 70 MPa (14.5 to 10000psi). The experiment was carried out by the OFI130-77 high temperature and high pressure rheometer. The experimental data were processed by multiple regression analysis method, and the mathematical model for predicting the apparent viscosity, plastic viscosity and yield point of water-based drilling fluid under high temperature and high pressure conditions was established. The experimental results show that when the temperature is lower than 65 °C (149 °F), the apparent viscosity and plastic viscosity of the water-based drilling fluid decrease significantly with increasing temperature. When the temperature is higher than 65 °C (149 °F), the apparent viscosity and plastic viscosity decrease slowly. Under low temperature conditions, the effect of pressure on the apparent viscosity and plastic viscosity of water-based drilling fluids is relatively significant. The calculated values of the prediction model have a good agreement with the experimental measurements. Compared with the traditional model, this prediction model has a significant improvement in the prediction accuracy in the low temperature section, which can provide a calculation basis for on-site application of deepwater drilling fluid.


Author(s):  
Wei-An Huang ◽  
Jing-Wen Wang ◽  
Ming Lei ◽  
Gong-Rang Li ◽  
Zhi-Feng Duan ◽  
...  

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Arild Saasen

Controlling the annular frictional pressure losses is important in order to drill safely with overpressure without fracturing the formation. To predict these pressure losses, however, is not straightforward. First of all, the pressure losses depend on the annulus eccentricity. Moving the drillstring to the wall generates a wider flow channel in part of the annulus which reduces the frictional pressure losses significantly. The drillstring motion itself also affects the pressure loss significantly. The drillstring rotation, even for fairly small rotation rates, creates unstable flow and sometimes turbulence in the annulus even without axial flow. Transversal motion of the drillstring creates vortices that destabilize the flow. Consequently, the annular frictional pressure loss is increased even though the drilling fluid becomes thinner because of added shear rate. Naturally, the rheological properties of the drilling fluid play an important role. These rheological properties include more properties than the viscosity as measured by API procedures. It is impossible to use the same frictional pressure loss model for water based and oil based drilling fluids even if their viscosity profile is equal because of the different ways these fluids build viscosity. Water based drilling fluids are normally constructed as a polymer solution while the oil based are combinations of emulsions and dispersions. Furthermore, within both water based and oil based drilling fluids there are functional differences. These differences may be sufficiently large to require different models for two water based drilling fluids built with different types of polymers. In addition to these phenomena washouts and tool joints will create localised pressure losses. These localised pressure losses will again be coupled with the rheological properties of the drilling fluids. In this paper, all the above mentioned phenomena and their consequences for annular pressure losses will be discussed in detail. North Sea field data is used as an example. It is not straightforward to build general annular pressure loss models. This argument is based on flow stability analysis and the consequences of using drilling fluids with different rheological properties. These different rheological properties include shear dependent viscosity, elongational viscosity and other viscoelastic properties.


2021 ◽  
Author(s):  
Mehrdad Gharib Shirangi ◽  
Roger Aragall ◽  
Reza Ettehadi ◽  
Roland May ◽  
Edward Furlong ◽  
...  

Abstract In this work, we present our advances to develop and apply digital twins for drilling fluids and associated wellbore phenomena during drilling operations. A drilling fluid digital twin is a series of interconnected models that incorporate the learning from the past historical data in a wide range of operational settings to determine the fluids properties in realtime operations. From several drilling fluid functionalities and operational parameters, we describe advancements to improve hole cleaning predictions and high-pressure high-temperature (HPHT) rheological properties monitoring. In the hole cleaning application, we consider the Clark and Bickham (1994) approach which requires the prediction of the local fluid velocity above the cuttings bed as a function of operating conditions. We develop accurate computational fluid dynamics (CFD) models to capture the effects of rotation, eccentricity and bed height on local fluid velocities above cuttings bed. We then run 55,000 CFD simulations for a wide range of operational settings to generate training data for machine learning. For rheology monitoring, thousands of lab experiment records are collected as training data for machine learning. In this case, the HPHT rheological properties are determined based on rheological measurement in the American Petroleum Institute (API) condition together with the fluid type and composition data. We compare the results of application of several machine learning algorithms to represent CFD simulations (for hole cleaning application) and lab experiments (for monitoring HPHT rheological properties). Rotating cross-validation method is applied to ensure accurate and robust results. In both cases, models from the Gradient Boosting and the Artificial Neural Network algorithms provided the highest accuracy (about 0.95 in terms of R-squared) for test datasets. With developments presented in this paper, the hole cleaning calculations can be performed more accurately in real-time, and the HPHT rheological properties of drilling fluids can be estimated at the rigsite before performing the lab experiments. These contributions advance digital transformation of drilling operations.


2021 ◽  
Vol 2057 (1) ◽  
pp. 012120
Author(s):  
E I Mikhienkova ◽  
A V Minakov ◽  
A V Matveev ◽  
S V Lysakov

Abstract A systematic study of the effect of nanoparticles of various concentrations and sizes on the rheological properties of various oil-based drilling fluids with nanoparticle additives has been carried out. The concentration of nanoparticles in drilling emulsions varied from 0.25 to 2 wt%, and the average size of nanoparticles ranged from 18 to 100 nm. As a result of numerous laboratory experiments, formulations and technology for the preparation of stable oil-based drilling fluids with additives of nanoparticles have been developed. The effect of nanoparticles on the viscosity and rheological properties of these drilling fluids has been studied.


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