Recovery of Lloydminster And Morichal Crudes By Caustic, Acid And Emulsion Floods

Abstract

Non-thermal oil recovery methods, such as caustic, acid and emulsion flooding, hold promisefor certain types of viscous oils under favourable conditions. This investigation was concerned with the recovery of the Lloydminster crude (Saskatchewan) and the Morichal crude (Venezuela) at the respective reservoir temperatures, using these three techni_ ques.Thefirstpartofthestudywascon-cerned with a systematic examination Pf the emulsification of each cru wit@ aqueous solutions, having pH's 1 nging from acid to basic. The Lloydi inster crude yielded both oil-in-water and water-in-oil emulsions, whereas the Morichal crude produced only water-in-oil emulsions, stable at the respective reservoir temperatures. The second part of the study involved core floods, utiliz-ing (I) selected emulsions, (ii) acid solu-tions and (iii) caustic solutions. The oil recovery in the case of the Lloydminster crude was 30 to 46% of the in-place oil, i.e., about 41 to 8801o greater than that obtainable by a waterflood. The type and size of the slug were the criticalfactors in determining recovery. The oil recovery in the case of the Morichat crude was 59 to 65%.In both cases, emulsion slugs were more effective than caustic or acid slugs. The paper discusses the drawbacks of such non-thermal methods, as well as conditions under which such methods are likely to be successful. Introduction & BaCkground In recent years, caustic flooding and emulsion flooding of viscous oil forma-tions have received a great deal of atten-tion, and hold considerable promise for the recovery of moderately viscous oils._ The status of these processes was recent-ly reviewed by Johnson(l). He discussed four principal mechanisms for caustic flooding: emulsification and entrap-ment, wettability reversal from oil-wet to water-wet, or vice versa, and emulsification and entrapment. In the case of viscous oils, it would seem that emulsification and entrapment is the dominant mechaniSM(2). The caustic reacts with the organic acids in the residual oil, leading to the formation of an oil-in-water emulsion in situ. ln a later-wet porous medium, the emulsion ciropiets move downstream with the flowing caustic, and are entrapped again in small pore throats. The over-all effect is a reduction in the water mobility, w'nich is beneficial in improving the volumetric sweep. The crucial factor determining the success of caustic flooding is the crude composition, and the nature of the polar compounds pre-sent. Ehrlich, Hasiba and Raimondi(3) describe an efficient screening method for this purpose. Cooke, Williams and r'ol.odzie(4) also outline guidelines for evaluating potential caustic floods.Emulsion flooding involves the preparation of the crude and water emulsion prior to injection, and offers a possible alternative if an emulsion can_ not be formed in situ.A number of laboratory studies of caustic flooding have been reported. Jennirigs(5) gives caustic solution -crude oil interfacial measurements for 164 crude oils from 78 fields. Almost all crude oils with API gravities of 201 or l...

Investigation into the Processes Responsible for Heavy Oil Recovery by Alkali-Surfactant Flooding

“…Some of the recovery mechanisms proposed have been reduction in the oil-water interfacial tension 19,20 , the generation of water-in-oil (W/O) emulsions 5,21,22 and the generation of oil-in-water (O/W) emulsions 4,23-26 . The fact that various researchers have identified different oil recovery mechanisms points to the complexity of interpreting these chemical floods.…”

“…While these viscous emulsions can lead to significant problems for production and transport of heavy oil, several researchers have investigated their application in improved heavy oil recovery. Dranchuk et al 31 and Farouq Ali et al 22 both observed that when caustic (alkaline) solutions were injected into sand packs containing viscous heavy oil, W/O emulsions would form and this corresponded to an improvement in the oil production rates and recovery factor. It was proposed 22 that the mechanism responsible for the improved oil recovery is that the more viscous W/O emulsion is able to displace the heavy oil in a more stable fashion.…”

Experiences With Waterflooding Lloydminster Heavy-Oil Reservoirs

“…Revised manuscript received June 2, 1982. Paper (SPE 10196) first presented at the SPE 56th Annual Technical Conference and Exhibition held in San Antonio Oct. [5][6][7]1981.…”

Investigation of synergy between nanoparticle and surfactant in stabilizing oil-in-water emulsions for improved heavy oil recovery

“…Both the conditions lead to improved sweep efficiency after water flooding. Previous studies have shown that emulsions could be used to increase water viscosity, decreasing mobility ratios resulting in a more efficient oil recovery [10][11][12][13][14][15]. Recent studies on the recovery of heavy oils by emulsion flooding have shown good potential for this recovery process in conjunction with water flooding [16][17][18].…”