Upward Gas-Liquid Flow in Concentric and Eccentric Annular Spaces

This paper presents a rigorous, mechanistic model for simulating a gas kick, that uses the thermodynamic approach to account for gas solubility. This thermodynamic solubility model uses the pressure and temperature data from the kick simulations and estimates the mole fraction of various gas components in the liquid phase. We validated these gas solubility results using Aspen HYSYS, a commercial chemical process simulation software. The thermodynamic solubility model presented in this paper assumes a pure-methane kick and applies the concepts of phase-equilibrium and fugacity to estimate the amount of dissolved gas in the drilling fluid. Application of fugacity equilibrium between the gas and liquid phases, in conjunction with the Peng-Robinson equation, gives the liquid phase mole fraction of methane. The analytical kick model uses the Hasan-Kabir two-phase flow modeling approach to describes the changes in pressure during kick migration, at various points in the annulus. Since the expansion of the gas bubbles depends on the variation in pressure, these studies also lead to pit gain estimates. A comparison between our model results and HYSYS values for methane liquid-phase mole fraction showed a maximum 8% deviation with complete agreement on bubble point (Pb) pressure and location estimates. Similarly, our model calculated the solution gas-oil ratio (Rs), with a maximum divergence of 3% from HYSYS estimates. From the comparison studies with other empirical Bo & Rs correlations, we note that the estimates of our model agreed best with those of O’Bryan’s (O'Bryan 1988) correlations. Many numerical kick simulators exist today, but they are notoriously time-consuming, limiting their on-field utility. Our kick simulator’s simplicity makes it potentially useful for on-field well control decisions. Most of these existing numerical simulators ignore the effects of kick solubility in synthetic-based muds. In the few models that do not ignore solubility, the approach to accounting for gas solubility and mud swelling is empirical, limiting their usage under conditions beyond the range of the source data used in developing these correlations. The mud swelling calculation approach we developed does not have these pressure and temperature range limitations.

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A Mechanistic Gas Kick Model to Simulate Gas in A Riser with Water and Synthetic-Based Drilling Fluid

Manikonda

Hasan

Barooah

et al. 2020

Day 1 Mon, November 09, 2020

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This paper presents a simple mechanistic model to describe a gas kick in a drilling riser with water-based mud (WBM) and synthetic-based mud (SBM). This model can estimate key kick parameters such as the change in the wellhead pressure, kick ascent time, and pit gain. In addition, this model also predicts the solubility of the gas kick in SBM at various depths in the annulus. We used the commercial chemical process simulation software, HYSYS, to validate the results of this solubility model. This paper also presents the gas kick experimental results from a 20-ft. tall vertical flow loop at Texas A&M University, Qatar. The base case investigates a gas kick in a vertical 10,000 ft. deep, 12.415 in. drilling riser with WBM. Our analytical model uses the Hasan-Kabir two-phase flow model and develops a set of equations that describe the pressure variation in the annulus. This computed pressure change allows estimates of pit-gain. Our experimental data comes from a 20-ft. tall flow loop with a 2.5 in. steel tube, inside a 4.5 in. Acrylic pipe, that simulates a riser. For these gas kick experiments, we injected specific amounts of gas at the bottom of the setup and recorded the bubble's expansion and migration. The mechanistic model predicted explosive unloading of the riser near the wellhead. A comparison between our model results and HYSYS values for methane liquid-phase mole fraction showed a maximum 8% deviation with complete agreement on bubble point (Pb) pressure and location estimates. Similarly, our model calculated the solution gas-oil ratio (Rs), with a maximum divergence of 3% from HYSYS estimates. From the comparison studies with other empirical Bo & Rs correlations, we note that the estimates of our model agreed best with those of O'Bryan's (Patrick Leon O'Bryan, 1988) correlations. Numerical kick simulators that exist today are notoriously time and power-intensive, limiting their on-field utility. Our mechanistic model minimizes computation time through its simple, analytical form to describe kick migration. Our model offers another layer of novelty through the analytical, thermodynamic solubility modeling as opposed to empirical modeling sused by most of the current gas kick simulators.

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Upward Gas-Liquid Flow in Concentric and Eccentric Annular Spaces

Cited by 3 publications

References 10 publications

Multiphase Flow Systems and Potential of Machine Learning Approaches in Cutting Transport and Liquid Loading Scenarios

Multiphase Flow Systems and Potential of Machine Learning Approaches in Cutting Transport and Liquid Loading Scenarios

A Gas Kick Model that Uses the Thermodynamic Approach to Account for Gas Solubility in Synthetic-based Mud

A Mechanistic Gas Kick Model to Simulate Gas in A Riser with Water and Synthetic-Based Drilling Fluid

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