An Improved Predictive Tool for Liquid Loading in a Gas Well

Abstract

As the search for natural gas becomes increasingly high due to its high demand worldwide, the oil and gas industry is faced with the challenge of liquid loading in gas or condensate wells. It is imperative to properly design and predict the operational parameters necessary for handling flow assurance challenges due to simultaneous flow of gas with liquid. The model of Guo et al is the most recent systematic approach for predicting liquid loading in gas well. However, it did not account for the accumulation and kinetic terms in the momentum energy equation used to estimate bottom-hole pressure in a gas/oil/water/solid four phase flowing well. The two neglected terms in Guo et al formulation have significant effects on the gas well operational parameters such as the minimum gas flow rate for preventing liquid loading. This paper presents an improved model that describes a systematic approach for estimating liquid loading in a gas well without neglecting any term in the fundamental momentum equation. The results obtained showed that at the early production time where initial transience at the onset of flow is experienced, the critical gas flow rate obtained from the new model is lower than that predicted from Guo et al model due to inclusion of accumulation term while at the later production time, the critical gas flow rate obtained becomes higher than that predicted from Guo et al model and increases as the transient period elapses. Results further show that at some point during production, the minimum energy required to lift liquids out of the wellbore is more than that required at the earlier stage of production. The new model is reasonable, reliable and better when compare with Turner et al and Guo et al models. It is useful for operators to refine their procedures and better manage the risk of liquid loading during natural gas production.

A new model for predicting liquid loading in a gas well

“…In this study, the 106 test points from field data employed by Turner et al (1969) were applied to compare the new method to Turner et al (1969), Guo et al (2005) and Fadairo et al (2013) models. The wells produced gas and condensate and/or water from either the tubing or annulus as in single tubing-dual string completions.…”

“…Belfroid et al (2008) however, opined that when making predictions on critical flow, inclination angle, flow regime, tubing outflow, reservoir inflow relations as well as the dynamic disturbance on the stability should be considered. Fadairo et al (2013) modified Guo et al (2005) model by including the accumulation and kinetic terms and time in the governing equations used to develop Guo's model because Guo model underestimated the flow rate. This paper utilizes a numerical integration approach to predict liquid loading.…”

“…Turner et al (1969) created the first liquid loading model by using the theory of critical velocity, Guo et al (2005) is one of the most recent systematic modification of Turners model but did not consider accumulation and kinetic terms which has significant effects on liquid loading. Fadairo et al (2013), even though considered the accumulation and kinetic terms; made use of an iterative method to obtain the critical flow rate. This paper presents an improved model that describes a systematic approach for estimating liquid loading in a gas well using numerical integration method while considering the accumulation term, kinetic term and time that Turner et al and Guo et al neglected.…”

Research on Critical Liquid-Carrying Model in Wellbore and Laboratory Experimental Verification

“…Liquid loading in the wellbore has many drawbacks-it creates a back pressure against the formation pressure and increases the instability of production, resulting in a significant reduction in output, or even shutdown ahead of time [6][7][8][9][10][11][12][13][14]. Therefore, some mitigation measures need to be taken to drain the wellbore.…”

A New Approach for Accurate Prediction of Liquid Loading of Directional Gas Wells in Transition Flow or Turbulent Flow

“…And the main cause of this phenomenon is that in the later period during the gas well production, the formation pressure, gas velocity, and liquid-carrying capacity will be reduced, and the part of formation water in the wellbore will stay in well bottom causing fluid accumulation [2,3]. Liquid loading will create an increased backpressure on the formation and reduce production pressure differential, which decreases the gas rate and even kills the gas well [4,5]. Based on the theory of hydrodynamics, the formation water can be drawn to the surface when current gas velocity is higher than critical gas velocity.…”