Screening, Evaluation, and Ranking of Oil Reservoirs Suitable for CO2-Flood EOR and Carbon Dioxide Sequestration

Abstract

Geological sequestration of CO2 in EOR operations has been recognized as one of the more viable means of reducing emissions of anthropogenic CO2 into the atmosphere in response to global climate change. This option, which lowers the cost of CO2 sequestration by recovering incremental oil, is particularly attractive in mature sedimentary basins, such as the Western Canada Sedimentary Basin where many oil pools are near depletion, and where most of the needed infrastructure is already in place. A method was developed for the rapid screening and ranking of oil reservoirs suited for CO2-flood EOR, which is particularly fit for a very large number of reservoirs as listed in eserves databases, and which does not require detailed reservoir engineering analysis. Oil reservoirs are screened on the basis of oil gravity, reservoir temperature and pressure, minimum miscibility pressure and remaining oil saturation, to determine their suitability for CO2 flooding, and an analytical method is used to calculate the incremental oil recovery at breakthrough and for any hydrocarbon pore volume (HCPV) fraction of injected CO2. In addition, the reservoir capacity for CO2 sequestration is calculated. eservoirs are ranked according to a set of criteria with corresponding assigned weights to identify and select the best-suited reservoirs for CO2 flooding and sequestration. The method was applied to 8,637 oil reservoirs listed in the 2000 Alberta reserves database. Of these, 4,470 passed the screening criteria and were ranked based on technical and performance characteristics. Preliminary calculations predict that 150 × 106, 422 × 106, or 558 × 106 m3, of additional oil could be produced from Alberta's reservoirs at breakthrough, and at 50% and 100% HCPVof injected CO2, respectively; meanwhile sequestering 127, 591 and 1,118 Mt CO2, respectively. Thus, geological sequestration of CO2 in Alberta oil reservoirs suitable for CO2 flooding could provide a means for significantly reducing anthropogenic CO2 emissions from major point sources while, at the same time, realizing an economic benefit. Introduction As a result of anthropogenic CO2 emissions, atmospheric concentrations of CO2 have risen significantly from pre-industrial levels, primarily as a consequence of fossil-fuel combustion for energy production. Circumstantial evidence suggests that the increase in greenhouse-gas concentrations in the atmosphere leads to climate warming and weather changes(1). In response to the need to avoid irreversible climate changes and the associated risks resulting from greenhouse effects, most of the developed world, including Canada, has committed to reduce by 2012 the release into the atmosphere of anthropogenic CO2 to levels below those of 1990. However, although the intensity of CO2 emissions has markedly decreased, Canada's emissions have increased steadily since 1990 as a result of economic development. Given the inherent advantages, such as large resources, availability, ease of transport and storage, and competitive cost, fossil fuels, which currently provide about 75% of the world's energy, will likely remain as a major component of the world's energy supply for at least this century(1, 2). In light of this, producing regions, such as Western Canada, need to find ways to both increase oil production and reduce CO2 emissions.

CO2Eor and Storage in Oil Reservoir

“…The US experience indicated that approximately 40% of the originally injected CO 2 is being produced in the producer wells and can be reinjected (Shaw et al, 2002;Hadlow, 1992). This suggests a "gross" CO 2 -retention efficiency of approximately 60% at CO 2 breakthrough if separation and reinjection is not considered after the breakthrough.…”

“…This suggests a "gross" CO 2 -retention efficiency of approximately 60% at CO 2 breakthrough if separation and reinjection is not considered after the breakthrough. Shaw et al (2002) presented a method to calculate the mass CO 2 storage capacity (M CO 2 ) in the reservoir during EOR operations, which is a function of the recovery factor, OOIP, and oil shrinkage:…”

“…The following preliminary technical evaluations were suggested for selecting oil reservoir for CO 2 EOR and storage before considering other economic criteria (Shaw et al, 2002): -screening for EOR and storage suitability; -technical ranking of suitable reservoir; -IOR and CO 2 storage capacity predictions. flood.…”

The study of a new development method which integrates CO2 huff and puff with factory fracturing in tight oil reservoirs

“…In recent years, nonconventional oil and gas reserve is taking a gradually increasing proportion, thus reservoir reform has become the "trump card" of petrol engineering technology [1][2][3][4]. The factory fracturing technology is commonly used for shale gas development in north America and has three major advantages: fast construction speed, short period of production, low cost of winning.…”

Investigation of CO2Sequestration during Cold Heavy Oil Production

“…Some believe that CO 2 -EOR in a conventional oil reservoir will result in increased carbon emissions from incremental oil production (IEA GHG, 2007); others believe that 40% (Shaw and Bachu, 2002;Hadlow, 1992) or up to two-thirds of the injected CO 2 is being produced and can be re-injected. In the Bati Raman heavy oilfield (9 ı to 15 ı API) in southeast Turkey close to the Turkish-Iraqi border, where immiscible displacement using CO 2 -EOR is in operation, approximately 1,700 tonnes of CO 2 are injected daily, 16 to 60% of which is recycled (Stevens et al, 2000).…”