Review of Practical Experience by Polymer Flooding at Daqing

Abstract

Summary This paper describes successful practices applied during polymer flooding at Daqing that will be of considerable value to future chemical floods, both in China and elsewhere. On the basis of laboratory findings, new concepts have been developed that expand conventional ideas concerning favorable conditions for mobility improvement by polymer flooding. Particular advances integrate reservoir-engineering approaches and technology that is basic for successful application of polymer flooding. These include the following:Proper consideration must be given to the permeability contrast among the oil zones and to interwell continuity, involving the optimum combination of oil strata during flooding and well-pattern design, respectively;Higher polymer molecular weights, a broader range of polymer molecular weights, and higher polymer concentrations are desirable in the injected slugs;The entire polymer-flooding process should be characterized in five stages--with its dynamic behavior distinguished by water-cut changes; -Additional techniques should be considered, such as dynamic monitoring using well logging, well testing, and tracers; effective techniques are also needed for surface mixing, injection facilities, oil production, and produced-water treatment; andContinuous innovation must be a priority during polymer flooding. Introduction China's Daqing oil field entered its ultrahigh-water-cut period after 30 years of exploitation. Just before large-scale polymer-flooding application, the average water-cut was more than 90%. The Daqing oil-field is a large river-delta/lacustrine facies, multilayered with complex geologic conditions and heterogeneous sandstone in an inland basin. After 30 years of waterflooding, many channels and high-permeability streaks were identified in this oil field (Wang and Qian 2002). Laboratory research began in the 1960s, investigating the potential of enhanced-oil-recovery (EOR) processes in the Daqing oil field. After a single-injector polymer flood with a small well spacing of 75 m in 1972, polymer flooding was set on pilot test. During the late 1980s, a pilot project in central Daqing was expanded to a multiwell pattern with larger well spacing. Favorable results from these tests--along with extensive research and engineering from the mid-1980s through the 1990s--confirmed that polymer flooding was the preferred method to improve areal- and vertical-sweep efficiency at Daqing and to provide mobility control (Wang et al. 2002, Wang and Liu 2004). Consequently, the world's largest polymer flood was implemented at Daqing, beginning in 1996. By 2007, 22.3% of total production from the Daqing oil field was attributed to polymer flooding. Polymer flooding boosted the ultimate recovery for the field to more than 50% of original oil in place (OOIP)--10 to 12% OOIP more than from waterflooding. At the end of 2007, oil production from polymer flooding at the Daqing oil field was more than 10 million tons (73 million bbl) per year (sustained for 6 years). The focus of this paper is on polymer flooding, in which sweep efficiency is improved by reducing the water/oil mobility ratio in the reservoir. This paper is not concerned with the use of chemical gel treatments, which attempt to block water flow through fractures and high-permeability strata. Applications of chemical gel treatments in China have been covered elsewhere (Liu et al. 2006).

Modification of a nicotinic acid functionalized water‐soluble acrylamide sulfonate copolymer for chemically enhanced oil recovery

“…The best result was obtained when the temperature changed to 60 C (Table III, entry 7). Neither increasing nor decreasing the temperature improved the result (Table III, The effect of the pH on the sulfomethylation was also investigated (Table III, entries [10][11][12][13][14]. We found that the reaction was quite sensitive to the pH value, and the synthesized copolymer gave poor results at both low and high pH (Table III, entries 10-14 vs entry 8).…”

“…6,7 Because of its feasible and economical operation and its ability to efficiently reduce the mobility ratio, polymer flooding has shown significant adaptability to existing reservoir conditions. [8][9][10] Partially hydrolyzed polyacrylamide (HPAM), one of the most widely used thickeners or modifiers in EOR, has been reported by many researchers. 11,12 However, the poor salt tolerance, temperature tolerance, and anti-shear ability of HPAM have seriously confined its application in oil fields.…”

Stability, seepage and displacement characteristics of heterogeneous branched-preformed particle gels for enhanced oil recovery

“…To date, polymer ooding has contributed to 10% of the original oil in place (OOIP) aer water ooding. 6 In most oil reservoirs, there are many layers of different permeability. Even a single layer can have a heterogeneous composition with numerous preponderance ow paths.…”

Investigation on Polymer Reutilization Mechanism of Salt-Tolerant Modified Starch on Offshore Oilfield

“…Polymer flooding, as a technically and commercially proven enhanced oil recovery (EOR) process, plays an important and effective role in the exploitation of onshore and offshore oilfields worldwide [1][2][3][4] . However, a large pore path appears in long-term polymer flooding, especially in high-heterogeneity reservoirs.…”