Application of Dispersed Particle Gel (DPG) Technology for Enhanced Oil Recovery and Water Production Management

Abstract

Abstract The objectives are to demonstrate design, selection and maturation of new Dispersed Particle Gel (DPG) particles for water production management and EOR in giant carbonate reservoirs. DPG technologies have been applied in conventional mature reservoirs, but the challenges addressed here are high temperature, high salinity, deep, heterogeneous carbonate reservoirs. A systematic approach was developed and implemented taking the technology from screening, laboratory tests to field piloting. Existing technologies were reviewed. DPG technology was selected based on our successful applications in mature reservoirs in China. An extensive DPG design study was performed to best match DPG chemical make-up, size, performance parameters against expected carbonate reservoir heterogeneity and harsh conditions. Candidate DPGs were taken to extended laboratory tests to ensure compatibility. Two best performing candidates were studied by dedicated analytical models and detailed compositional sector models. Large scale deployment was assessed. Based on favourable deployment economics, field pilot candidates were ranked and selected, and high level design is completed. The Onshore Abu Dhabi carbonate reservoirs have relatively long production history, with water breakthrough seen in certain areas. For delaying/arresting water-cut increase and EOR targeting low permeability poorly flooded areas, linked polymer solution (LPS), colloidal dispersion gel (CDG) and pre-preparation particle gels (PPG) are not suitable due to high reservoir temperature and salinity. Polymer microspheres are difficult to control. DPG was selected, composed of functional polymer and different cross-linkers (PEI, FL103, HEX-RE, and PY accelerator). Extensive laboratory tests were performed with reservoir cores, covering DPG viscosity shear properties, thermal/pressure/salinity stability and injection performances. The final DPG candidates have wide distribution of sizes, low viscosity, shear resistance, excellent self-growth and coalescence ability, compatibility up to 150 oC and salinity 300,000 ppm. Significantly, technologies were tested successfully for DPG production, on-site preparation and injection. Based on dedicated analytical models and fine scale compositional model simulation, potential field pilots were studied using laboratory measurements as input. Uncertainty analysis were performed. Project economics for potential large scale deployment were generated based on a range of DPG performances, and are competitive. High level Pilot design is completed with multi pilot candidates. Although DPG technology has been applied in conventional mature reservoirs, this paper shares the work performed advancing the technology to the combined extremely high temperature (up to 150 oC) and high salinity (up to 300,000 ppm) heterogeneous carbonate reservoirs. It represents a world first for such applications. A comprehensive approach was adopted: from existing field applications to extensive theoretical analysis and accelerated laboratory tests, field operational considerations, etc. It is hoped that this work can provide discernment for operators with similar requirements.