Experimental investigation on precipitation damage during water alternating flue gas injection

Abstract

<jats:p>Water Alternating Gas (WAG) approach can improve the efficiency of gas flooding. However, the precipitation damage that is induced by the gas injection may be inevitable. The precipitation pressure point test of gas injection, and the WAG parallel double-tube long-core flooding experiment under different injection conditions were systematically performed to obtain the optimum injection parameters. The variations of petrophysical properties were caused by precipitation, and its morphology was also determined by centrifugal capillary force and environmental scanning electron microscope. The precipitation pressure rised with the increase of the amount of gas injection, generally 2.0 MPa ~ 3.0 MPa higher than the bubble point pressure (<jats:italic>P</jats:italic><jats:sub><jats:italic>b</jats:italic></jats:sub>), and it was confirmed by X-ray energy spectrum and scanning electron microscope that the precipitation was mainly asphaltene. The optimum injection parameters for WAG were Gas–Water Ratio (GWR) of 1:1 and slug size of 0.1 HydroCarbon Pore Volume (HCPV), which benefited the recovery of low-permeability and high-permeability pipe by additional recovery of 28.5% and 17.4% respectively, while WAG process enhanced the total oil recovery by 23.4%. The pore volume and median radius of capillary pressure of all cores were both reduced with more obvious effects on conglomerate. Combined with the results of sediment saturation, it also showed the poorer the physical properties of the cores, the severer the influence of the precipitation. Overall, the WAG could greatly improve the recovery but the influence of precipitation must be considered.</jats:p>

The effects of porosity and permeability changes on simulated supercritical CO2 migration front in tight glutenite under different effective confining pressures from 1.5 MPa to 21.5 MPa

“…In a WAG process, SC‐CO 2 is injected after the previous water injection and it contacts with oil after breaking the water layers 48 . This work aimed to track the CO 2 plumes and breakthrough time in the sample under different ECPs.…”

Study on Damage Mechanism of Waterflooding Development in Weizhou 11-4N Low-Permeability Oilfield

“…The experimental results show that the formation water type is NaHCO 3 , while the injection water type is MgCl 2 . According to the difference in ion and salinity of formation water and injection water, there is a potential incompatibility problem [21][22][23][24][25][26][27].…”

Advancements, Challenges, and Perspectives of Flue Gas Injection in Subsurface Formations: A Comprehensive Review

“…An essential parameter for enhancing the performance of the operation is the determination of the optimal GOR in WAG operations. 130 Another challenge associated with flue gas injection operations is the corrosion of downhole strings and devices, primarily caused by the presence of corrosive gases such as CO 2 , O 2 , SO 2 , and H 2 S within the composition of the injected flue gas. In deep reservoirs with high pressure and temperature, device corrosion occurs at an accelerated rate due to the flue gas injection.…”

“…These studies aim to understand the impact of factors such as reservoir temperature and depth on the injection process, as well as to develop strategies for optimizing the overall performance of flue gas injection methods. 39,142 Wang et al 130 investigated the WAG injection in an oil reservoir with flue gas injection in Xinjiang Oilfield. In accordance with the imaging methods such as scanning electron microscope and energy spectrum analysis, flue gas injection increased the oil recovery factor by about 20% compared to traditional water injection method.…”