Alkali-Surfactant-Polymer Flooding Pilot Test in Southern Oman

Abstract

Petroleum Development Oman is advancing a pattern flood pilot in a major sandstone field in Southern Oman that uses a chemical EOR flooding process to recover additional reserves. An EOR screening study showed that Alkali-Surfactant-Polymer is a viable technology for this viscous oil reservoir (90 cP). A successful ASP pilot test will pave the way to potentially implement the process in other sandstone fields in the Southern Oman Basin. The ASP pilot test is a unique project in which two anionic surfactants have been specifically designed for the actual reservoir conditions. Laboratory tests indicated significant and comparable recovery from both outcrop and field cores. A high molecular weight polyacrylamide polymer designed to provide a favorable mobility ratio has also been tested at in-situ conditions. The primary objectives of the ASP pilot test are to validate laboratory results, demonstrate long term injectivity of the viscous ASP solution, reduce the range of technical and economic uncertainties associated with recovery efficiency and field operations and obtain data to calibrate dynamic models for accurate full-field predictions and economics. The field pilot consists of a 1.4 acres inverted 5-spot pattern that includes 4 corner vertical oil producers, 1 central injector and 2 observation wells. The 53m producer-to-injector distance enables early ASP flood response (4 to 5 months) and ensures completion of the field trial within one year of injection. Injection/production facilities will be skid-mounted and located in the vicinity of the pilot wells. Pilot commissioning and first ASP injection is anticipated to start in mid 2014. This paper presents both subsurface and facility aspects of the ASP pilot test design, including four successful single-well ASP/SWCT field tests, one ASP flood MicroPilot, and the experimental results of oil-water-ASP emulsion separation experiments.

Review of Important Aspects and Performances of Polymer Flooding versus ASP Flooding

“…Although ASP flooding seems promising in the laboratory as a tertiary recovery method, field experience has revealed several complicating features of the technology. Thus, it has been observed that the main problems while ASP flooding is related to operational arrays [12][13][14][15]. The scaling problem is the most common among ASP flood projects, and it creates the need to redesign surface facilities from ASP solution preparation units to production and processing units.…”

“…Therefore, potential emulsification issues should be envisaged preliminary as it was done in the Bhagyam field having additional demulsifier injection wells near producers [12]. Also, Finol et al [13] have reported preliminary laboratory experiments on identifying cost-effective demulsifiers in the designing stage of the Al Khalata pilot test.…”

“…Furthermore, polymer flooding (PF) is often the most feasible chemical EOR technology. Especially, polymer flooding has prominence, where ASP/SP flooding is not profitable and causes serious on-site problems (scaling, uptime decrease, injectivity issue, hard-to-break emulsions) [12][13][14][15]. In addition, this paper describes the economic viability of ASP flooding based on some field case studies from the literature.…”

Essentials of Upscaling Surfactants for EOR Field Projects

“…ASP or SP is a logical extension and has the promise to liberate the trapped oil. Consequently, there are several pattern-flood pilots in progress or about to be executed to evaluate ASP at a scale relevant to commercial scale application [14][15][16][17][18][19][20][21][22].…”

Experimentally investigation of the effects of nanoparticles‐enriched ASP formulations on the spontaneous imbibition in a fractured sandstone reservoir

“…[1--4] The ASP flooding with water, under favorable conditions, can lead to mobilization of the residual oil and improved displacement efficiency. [5,6] Even though success of the ASP has been mostly demonstrated in laboratory test, ASP flooding is very sensitive to heterogeneities in the reservoir, and it is necessary to have a comprehensive investigation of ASP flooding in reservoirs with different petrophysical properties for a wider and more successful implementation. [4] Surfactant solution tends to decrease the interfacial tension (IFT) between oil and injected fluid, altering the reservoir wettability toward water-wetted one, and improves the sweep efficiency through creating macroemulsions or microemulsions with oil and water.…”