A Survey of North Sea Enhanced-Oil-Recovery Projects Initiated During the Years 1975 to 2005

Abstract

Summary This paper provides a summary and a guide of the enhanced-oil-recovery (EOR) technologies initiated in the North Sea in the period from 1975 until beginning of 2005. The five EOR technologies that have been initiated in this region are hydrocarbon (HC) miscible gas injection, water-alternating-gas (WAG) injection injection, simultaneous water-and-gas (SWAG) injection, foam-assisted WAG (FAWAG) injection, and microbial EOR (MEOR). Each EOR technology that has been initiated in the North Sea was identified with its respective maturity level and/or maturation time frame, technology use restrictions, and process efficiency on the basis of incremental oil. Apart from WAG at Ekofisk and FAWAG at Snorre central fault block (CFB), all technologies have been applied successfully (i.e., positive in economic terms) to the associated fields. HC miscible gas injection and WAG injection can be considered mature technologies in the North Sea. The most commonly used EOR technology in the North Sea has been WAG, and it is recognized as the most successful EOR technology. The main problems experienced were injectivity (WAG, SWAG, and FAWAG projects), injection system monitoring, and reservoir heterogeneities (HC miscible gas injection, WAG, SWAG, and FAWAG projects). Approximately 63% of all the reported EOR field applications have been initiated on the Norwegian continental shelf (NCS), 32% on the UK continental shelf, and the remainder on the Danish continental shelf. Statoil has been the leader in conducting EOR field applications in the North Sea. The majority of future research will concentrate on microbial processes, CO2 injection, and WAG (including SWAG) injection schemes. In this review, laboratory techniques, global statistics, simulation tools, and economical evaluation were not considered and are considered outside of the scope of this paper.

Using New Synthesis Zirconia-Based Nanocomposites for Improving Water Alternative Associated Gas Tests Considering Interfacial Tension and Contact Angle Measurements

“…The density and pH of the prepared nanofluids at different concentrations are presented in Figure 7 within the range of 0.9991 and 0.9998 g/cm 3 . With increasing the NC concentration from 25 to 150 ppm, the density increased from 0.9991 to 0.9998 g/cm 3 , respectively.…”

“…2 Increasing sweep efficiency up to 10% in the WAG method was the main reason for using this method in a number of laboratory and field studies, such as Stafjord. 3,4 Moreover, laboratory experiments were shown that the WAG method had better performance, and it is known as a cost-effective method in comparison to the gas injection method, especially in heterogeneous reservoirs. 5−7 The main reasons for using the WAG method are preventing fingering issues, lowering the mobility ratio, and improving interfacial and wettability conditions.…”

“…The water alternative gas (WAG) method was introduced in 1987, and the main idea of using this EOR method was to combine primary water flooding and gas injection to increase ultimate recovery . Increasing sweep efficiency up to 10% in the WAG method was the main reason for using this method in a number of laboratory and field studies, such as Stafjord. , Moreover, laboratory experiments were shown that the WAG method had better performance, and it is known as a cost-effective method in comparison to the gas injection method, especially in heterogeneous reservoirs. − The main reasons for using the WAG method are preventing fingering issues, lowering the mobility ratio, and improving interfacial and wettability conditions. − We did a comprehensive study on different EOR scenarios, such as water/hot water and WAG (water, hot water, N 2 , CO 2 , and associated gas), and it was found that performing the WAG test with associated gas had the best values with regard to ultimate oil recovery and breakthrough time . Chemically enhanced WAG was introduced as an EOR method using different methods such as surfactant, polymer, and alkaline flooding, , and the main notion for using these methods was to solve the water blocking problem in routine WAG tests.…”

Simulation of muon radiography for monitoring CO 2 stored in a geological reservoir

“…Independent of the setup, liquefied or supercritical CO 2 can be subsequently piped to an on-shore or off-shore geological storage site, of which there are already numerous examples [4]. In the context of this paper we consider off-shore sites, which may be more commercially attractive due to the prospect of enhanced oil recovery [18,19].…”

Experimental Studies of Immiscible High-Nitrogen Natural Gas WAG Injection Efficiency in Mixed-Wet Carbonate Reservoir

“…It is considered that about 80% of the USA WAG field implementations were profitable [1,10]. WAG processes have also been successfully applied in the North Sea oil fields such as Snorre, Gullfaks, Ekofisk, Statfjord and Brage [11]. The review of 72 WAG field cases indicates that the average incremental recovery was around 10%, and in some cases, up to 20% of the Original Oil in Place (OOIP) [3].…”