41st Gas-Lift Workshop Houston, Texas, USA June 3 - 7, 2019 Paraffin Inhibition in the Tubing using Thermodynamics principle of Gas Lift Technology Kenechukwu Nwankwo (Chevron Nigeria Ltd.) 2019 Gas-Lift Workshop June 3 - 7, 2019

THERMODYNAMICS PARAFFIN INHIBITION OUTLINE Introduction Problem Statement and Objective Historical Performance of Case Study wells Pertinent Data Gas Lift Valve Design Results Conclusions and Recommendations KEY MESSAGES Currently not leveraging optimally on gas lift technology to prevent wax deposition High temperature gas lift source stream prevented paraffin deposition in tubing Productivity and cost management were also enhanced. Unlike chemical, thermodynamics inhibition is free of operating challenges

INTRODUCTION Gas Lift uses the principle of lowering hydrostatic head to optimize productivity. Gas lift operations mitigate problems like sand production, SCSSV opening, flow continuity etc. Gas lift operations have been utilized to manage wax production in the tubing by chemical paraffin inhibition Thermodynamics principle was utilized in this study to optimally manage wax deposition with minimal cost 2019 Gas-Lift Workshop June 3 - 7, 2019

INTRODUCTION – Gas Lift Principle The operating pressures, gas lift valve positions, and gas injection rates are all monitored and controlled at the surface enabling improved reservoir production. These values are dependent on specific well conditions. 2019 Gas-Lift Workshop June 3 - 7, 2019

PROBLEM STATEMENT/OBJECTIVE Wax deposition in tubing and flowlines is a significant contributing factor to higher operations cost in the petroleum industry (Newberry and Barker, 1985). Remediation methods all come at periodic costs – Intervention costs Deferred production which are not favorable to the oil industry at large. Two case study wells(A-01/A-02) were used to prove the efficacy of thermodynamics inhibition. 2019 Gas-Lift Workshop June 3 - 7, 2019

HISTORICAL PERFORMANCE OF CASE STUDY WELLS PRE-PARAFFIN INHIBITION PERFORMANCE Production trends from the wells were incoherent before paraffin inhibition Wells were designed with Gas Lift Mandrels because the Solution GOR 2019 Gas-Lift Workshop June 3 - 7, 2019

HISTORICAL PERFORMANCE OF CASE STUDY WELLS STATIC BOTTOM HOLE ANALYSIS BEFORE GAS LIFTING A-01 liquid level was encountered at 2200ft as seen in the plot above while that of A-02 is at the surface A-02 dummy valve at the second position was not holding pressure as can be deduced from the profile 2019 Gas-Lift Workshop June 3 - 7, 2019

PERTINENT DATA Well fluid’s oil gravity of over 34 degree API were not typical of wax producers. Wells were designed with Gas Lift Mandrels in the Tubing that are dummied out. 2019 Gas-Lift Workshop June 3 - 7, 2019

VISCOSITY TREND Viscosity trend from PVT models showed drastic increase with decrease in pressure and temperature Increasing Temperature was found to be a reliable means to address Paraffin Depositional issues 2019 Gas-Lift Workshop June 3 - 7, 2019

GAS LIFT VALVE DESIGN The orifice for A-01 and A-02 are at the fifth and second mandrels positions respectively. The remaining mandrels were dummied to replicate a one point operating gas lift system. 2019 Gas-Lift Workshop June 3 - 7, 2019

RESULTS: WAT AND FLOW LINE TEMPERATURE PROFILE Wax appearance temperature dropped due to lightening and heating of the oil column with the Gas Lift gas. Flowline Temperature increased due to the internal heat derived from the Gas lift gas. Flow assurance was achieved by the two processes above 2019 Gas-Lift Workshop June 3 - 7, 2019

RESULTS: STATIC BOTTOM HOLE ANALYSIS AFTER GAS LIFTING Liquid level is more distinctive(sharper front) because of the decrease in viscosity due to increased Temperature effect from the gas lift stream Temperature gradient within the oil column was stable- implying adequate heat retention/distribution 2019 Gas-Lift Workshop June 3 - 7, 2019

RESULTS: PRODUCTION IMPACT FROM FLOW ASSSURANCE Improved productivity realized from this flow assurance strategy Production became stable (no down time) A total gain of 1000 BOPD realized from both wells. Increase in water cut Compressor pressure drop 2019 Gas-Lift Workshop June 3 - 7, 2019

CONCLUSIONS AND RECOMMENDATION Gas Lifting can also be a best Practice in flow assurance apart from Productivity optimization Increasing Gas lift temperature for waxy well fluids can prevent wax formation Wells with high water production and salts concentration need further analyses to manage scale and wax deposition One-point gas lift valve injection system is recommended for flow assurance best practice because of the challenges of temperature variation across valves Wells on chemical paraffin inhibition should be reviewed for flow optimization and cost management opportunities. 2019 Gas-Lift Workshop June 3 - 7, 2019

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