Review of Practical Experience & Management by Polymer Flooding at Daqing

Abstract

Abstract This paper describes successful experiences employed during polymer flooding at Daqing that will be of considerable value to future chemical floods, both in China and elsewhere. Based on laboratory findings, new thoughts have been developed that expand conventional ideas concerning favorable conditions for mobility improvement by polymer flooding. Particular advances integrate reservoir engineering approaches and technology which is elementary for successful application of polymer flooding. These include:Considering permeability differential among the oil zones and interwell continuity, optimizing the oil strata combination and well pattern design.The injection procedures and injection formula are the key points when designing a polymer flood project. These points include:profile modification is needed before polymer injection and zone isolation is of value during polymer injection, higher molecular weight of the polymer used in the injected slugs, large polymer bank size, higher polymer concentrations and injection rate based on the well spacing and injection pressure.Characterizing the entire polymer flooding process in five stages, with its dynamic behavior distinguished by the water cut changes. Additional techniques involved with reservoir engineering should also 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. Continuous innovation and effective response to new challenges must be a priority during polymer flooding. New directions and opportunities at Daqing will (1) explore the feasibility of polymer flood application in poorer ("third-class") strata, (2) to identify new polymers to suit portions of the reservoir with higher temperatures and higher water salinities, and (3) continually see improvements in our approach to polymer flooding. Introduction Laboratory research began in the 1960s, investigating the potential of enhanced oil recovery (EOR) processes in the Daqing Oil Field. For polymer flooding technology, from a single-injector polymer flood with small well spacing began in 1972. During the late 1980s, a pilot project in central Daqing was expanded to a multi-well pattern with larger well spacing. Favorable results from these tests—along with extensive research and engineering from mid 1980 through the 1990s—confirmed that polymer flooding was the method of choice to improve areal and vertical sweep efficiency at Daqing, as well as providing mobility control.1,2 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 should boost the ultimate recovery for the field to over 50% original oil in place (OOIP)—10–12% OOIP more than from water flooding. At the end of 2007, oil production from polymer flooding at the Daqing Oilfield was more than 10 million tons (73 million barrels) per year (sustained for 6 years). Recently, the industrial application has been expanded into the second-class, less-permeable strata.