Maximizing Profitability and Sustainability, Minimizing Carbon Footprint in Gas Recycle Developments by Optimizing Gas Injection Parameters to Conform to Dynamic Changes in Reservoir Performance
Authors: Almaazmi Juma , Arianto Muhammad , Almenhali Salem , Almansoori Shamma , Almuntheri Hiyam , Karamessinis Aristeidis , Al Sayegh Ahmed , Ahmad Mubashir 
Published: October 2022

Abstract

Technical Category
41. Energy Efficiency and Sustainability

Abstract Title
Maximizing Profitability and Sustainability, Minimizing Carbon Footprint in gas Recycle Developments by Optimizing gas Injection Parameters to Conform to Dynamic Changes in Reservoir Performance

Objectives/Scope
The Discharge Pressure Optimization project was initiated as a collaborative effort between ADNOC Onshore and ADNOC Gas Processing in order to assess the feasibility of lowering the re-injection compressor's discharge pressure. Lowering the discharge pressure has immediate cost and environmental benefits, however, it may result in affecting the ultimate condensate recovery if not done correctly. A solution was developed to achieve this requirement without affecting the recovery while resulting in significant OPEX savings ($1MM/year) and considerable reduction greenhouse gas emissions and carbon footprint. A field trial was conducted to assess the applicability of the solution.

Methods, Procedures, Process
The solution approach is primarily focused on three sets of pressure readings: discharge pressure outlet, upstream choke and downstream choke conditions. The data was charted (using weighted average of all wells) for a period of 6 months where a consistent pressure loss was observed across the well chokes. This meant that discharge pressure could be lowered if supplemented by adjusting injection well chokes such that the original injection rate and downhole flowing pressure of the wells are retained. A field trial was conducted to test this approach followed by long-term simulation model impact assessment.

Results, Observations, Conclusions
AON and AGP agreed to test the solution in a trial that was conducted for a period of 2 weeks. The field trial entailed lowered the discharge pressure at certain pressure decrements up to a maximum of 8% reduction. Each pressure reduction step was followed by beaning the well choke till the original injection rate and pressures were retained. The field trial observed a retention in injection parameters for all but five of the wells. Two of the wells indicated a complete cessation of flow, while the other three observed a 50% drop in injection rate. The next step involved utilizing the dynamic model to assess the impact these wells would have on the condensate recovery in their current state. In terms of overall condensate recovery, operating at 360 bar (5% reduction) appeared to be optimum while resulting in negligible condensate recovery change. Meanwhile, the new operating discharge pressure of 360 would yield an approximate energy saving of 900,000USD and a 23 ton reduction in greenhouse gases emissions per year.

Novel/Additive Information
The approach used is easily scalable on any recycle reservoir system, which can yield higher operating cost efficiency and emissions reduction opportunities to minimize carbon footprint of E&P operations in line with ADNOC's sustainability strategic pillar.