Experimental Investigation of Noble Viscoelastic Surfactant and Chelating Agent for Heavy Oil Enhanced Oil Recovery in High‐Pressure–High‐Temperature Carbonate Reservoirs

Abstract

The success of chemical enhanced oil recovery (cEOR) is significantly dependent on the type of reservoir and its pressure and temperature conditions. The recovery of heavy oil from carbonate reservoir using cEOR method is still challenging because of its highly complex internal structures and high pressure–high temperature (HPHT) conditions. This research work is the first account of the use of AGA‐97 (viscoelastic surfactant [VES)) along with a chelating agent diethylene triamine penta acetic acid (DTPA) for their application in cEOR method in heavy‐oil‐carbonate reservoirs. Several core flooding experiments were carried out to ascertain the effectiveness of the VES AGA‐97 and chelating agent for cEOR method. The effect of VES on viscosity and interfacial tension was also studied with varying concentration, temperature, and time. The thermal stability of VES was analyzed with the help of thermogravimetric analysis, nuclear magnetic resonance (NMR) and Fourier‐transform infrared spectroscopy. VES AGA‐97 was found to have high thermal stability in short‐term aging. The static adsorption and dynamic adsorption of VES AGA‐97 was studied with the help of total organic carbon analysis. After all the analysis, it was found that VES AGA‐97 and DTPA can be effectively used for cEOR method in carbonate reservoir at HPHT conditions, and the total additional oil recovery of 5.82–9.64% may be achieved.

The Synergetic Impact of Anionic, Cationic, and Neutral Polymers on VES Rheology at High-Temperature Environment

“…MgCl 2 and CaCl 2 showed an increase in solution elasticity more than NaCl, KCl, and NH 4 Cl [ 14 ]. For VES micellar in CaBr 2 and CaCl 2 brines, adding MgO or ZnO nanoparticles increased thermal stability and viscosity at varied shear speeds [ 23 ].…”

“…A substantial amount of oil remains untapped during waterflooding as water prefers the path with the least resistance [ 23 ]. Sweep efficiency during waterflooding could be improved using polymers, which increases fluid viscosity and elasticity.…”

“…They studied viscosity and interfacial tension at different concentrations, temperatures, and times. It resulted in an efficient displacement and reduced the interfacial tension [ 23 ]. Short-term testing of the VES samples at high temperatures showed strong thermal stability; however, aging the samples at high temperatures increased their IFT over time [ 23 ].…”

Enhancing the Oil Recovery from Naturally Fractured Reservoirs Using Viscoelastic Surfactant (VES) Flooding: A Field-Scale Simulation

“…It provides better displacement of the trapped fluid and recovers the remaining oil by reducing the IFT; thus, it has the qualities of both surfactants as well as polymers. 10 , 16 − 18 In general, viscoelastic fluids are non-Newtonian fluids and they combine both elastic and viscous properties. 19 During VES flooding, the injected fluids mobilize the remaining oil by improving the mobility ratio and reducing the IFT.…”

“… 23 A viscoelastic surfactant has excellent thermal stability and resistivity to salinity, and thereby VES flooding can significantly enhance the oil recovery from both sandstone and carbonate reservoirs. 11 , 14 , 16 − 18 …”