THAI - 'Toe-to-Heel Air Injection', is a radically new process, which remedies the problems associated with conventional in-situ combustion (ISC). Conventional ISC operates as a long-distance displacement process (Figure1), due to the conventional well-spacing arrangement used. THAI is an integrated horizontal wells process, and operates via short-distance displacement, as shown in Figure 1. It therefore falls into the same category of heavy oil processes as SAGD (Steam Assisted Gravity Drainage) and VAPEX (Vapor Extension, of SAGD). In THAI, heavy oil, which is mobilized in the Mobile Oil Zone (MOZ), ahead of the combustion front (Figure1), drains into the open section of the horizontal producer a short-distance below. Typically, this is only a few tens of metres, in contrast to 100's of metres for conventional, long-distance displacement.
THAI operates in a HTO mode (high temperature oxidation), typically 450 to 600 º for a heavy oil reservoir. This is absolutely essential to maintain vigorous in-situ combustion, and avoidance of LTO (low temperature oxidation). Over 50 three-dimensional combustion cell experiments, at low pressure, have been performed by the Bath IOR Group. A typical set of results for Athabasca Tar Sand bitumen is shown in Figure 1. The THAI process can be applied to heavy or medium heavy oil (e.g. West of Shetlands Clair oil demonstrated very good combustion characteristics), and can be operated in primary or secondary/tertiary mode (post-waterflood, - cold production, -steamflood). The process is very stable, due to the near-vertical combustion front, as shown by the STARS numerical simulation for Wolf Lake Oil in Figure 2. Oxygen breakthrough into the horizontal producer well is prevented by the (mainly) forced flow displacement in the MOZ, which acts to control gas override. Residual fuel (coke) deposited in the lower part of oil layer creates a 'sealing' or permeability profiling effect, directing injected air towards the high temperature combustion zone, in the upper part of the oil layer. The principal benefits of THAI are: very high oil recovery, 80-85% OOIP; substantial in-situ upgrading (6-8 ºAPI) - worth 40 ¢ for every API point); high thermal efficiency and substantial environmental benefits, including reduction of S (30-40%),N (>90%),heavy metals (>90%). The process also generates power station amounts of energy in the reservoir. If recovered, it could provide most of the energy to run upstream operations and surface facilities, and contribute towards creating a sustainable IOR process.
CAPRI: this process is a catalytic extension of THAI. A standard refinery hydrotreating catalyst (NiMo/CoMo) is employed, gravel-packed, around the horizontal producer well (Figure 2). Lighter oil in the MOZ (thermally cracked) is displaced and caused to flow over the annular layer of catalyst and into the horizontal producer well. CAPRI achieves an 8 ºAPI upgrading, additional to that achieved by THAI. There is the potential, therefore, to in-situ upgrade a heavy oil or bitumen of 8-10 ºAPI gravity, virtually to a light oil of 24-26 ºAPI (Figure 2), in a one-step downhole process. This downhole technology has potential to make huge savings on the cost of surface upgrading plant by using the reservoir as a downhole reactor.
Future research is targeted at modelling reaction kinetics for various heavy crudes, bitumen and also medium-heavy oils (especially in relation to the North Sea ). Other topics are reservoir heterogeneity, bottom water and gas cap reservoirs, and start up protocols.
The_Virginian wrote:Any body have the scoop on the trials in California?
The_Virginian wrote:Any body have the scoop on the trials in California?
I just have a hard time accepting parroted theoretical figures from the co.'s website.
This is important to know, if these folks are successful, the effects of PO would be delayed 20 years.... Suadi Arabia could be left to it's own devices, and so many other changes would make all of our planning and flustering temporarily irrelevant.
THAI™ offers many potential advantages over SAGD, including higher resource recovery (70–80) percent of the original oil-in-place, lower production and capital costs (one horizontal well and no water treating and handling), minimal usage of natural gas and fresh water, a partially upgraded crude oil product, reduced diluent requirements for transportation, and significantly lower greenhouse gas emissions. The THAI™ process also has potential to operate in reservoirs that are lower in pressure, containing more shale, lower in quality, thinner and deeper than SAGD.
Because we don't inject steam, water rates in THAI™ are low- only 10% of those for SAGD. Also there will be no need to purify the water for re-use. Unlike SAGD, the high heat (plus 400°C) generated by the THAI™ process “flashes” most of the reservoir water producing low-salinity water. Produced water is expected to be of industrial quality after standard biological treatment to remove organics. Because of the low volumes involved in the THAI™ pilot, produced water will be sent to a disposal well.
The THAI™ process is more Kyoto friendly. Natural gas is not burned to produce steam therefore CO 2 emissions are lower. Heat from produced fluids and combusted solution gas can be used for power generation, replacing power generated from coal. Less energy is required to pipeline the upgraded oil without added diluent. The high-energy process of refinery coking will not be needed, further reducing emissions.
The expected air/oil ratio is 1,500 m³ air/m³ oil or 8.4 mscf/bbl. The energy for this is well below the energy required to generate high- pressure steam in the SAGD process. Although energy from hot combustion fluids will not be harnessed in the pilot, there is ample energy available to drive the air compressors and make the process energy-self-sufficient.
PETROBANK FIRES UP WHITESANDS THAI'TM' PROJECT
Petrobank Energy & Resources Ltd. has completed the preignition heating cycle (PIHC) on the first well pair at the Whitesands project and commenced air injection on July 20, 2006.
During the PIHC phase, communication between the vertical injection well and the horizontal production well was established by injecting steam in the vertical well located at the toe of the horizontal well. This process developed an expanding hot mobile bitumen zone, and established fluid flow between the injection well and the horizontal production well. During this phase, steam was also circulated in the horizontal production well to aid in the PIHC and to enable high total fluid production rates from the horizontal well. During these operations, the horizontal production well achieved total production rates of up to 1,000 barrels of fluid per day, consisting primarily of condensed steam and formation water and up to a 15-per-cent oil cut of 11-degree API bitumen. By establishing communication between the two wells and introducing a large amount of heat energy into the reservoir to create the mobilized bitumen zone around the vertical well, conditions were determined to be appropriate for the initiation of air injection and to cause in situ combustion.
As the company commences air injection, temperature readings from thermocouples in observation wells near the vertical injection well and in the horizontal production well are expected to show an increase in temperature as the combustion front expands. A period of time will be required for the complete transition from the PIHC production phase into production via the Thai process. Produced fluid and gases will be continuously monitored, and wellbore and reservoir temperatures and pressures will be constantly measured in order to manage the rate at which air injection volumes are increased, the progression of the combustion zone and to optimize surface facilities operations. The company will begin the PIHC phase on the second of the three well pairs once combustion on the first well pair has stabilized.
The Thai process
Thai is an evolutionary in situ combustion technology for the recovery of bitumen and heavy oil that combines a vertical air injection well with a horizontal production well. Thai integrates existing proven technologies and provides the opportunity to create a step change in the development of heavy oil resources globally. During the process, a high-temperature combustion front is created underground where part of the oil in the reservoir is burned, generating heat, which reduces the viscosity of the remaining oil allowing it to flow by gravity to the horizontal production well. The combustion front sweeps the oil from the toe to the heel of the horizontal producing well, recovering up to an estimated 80 per cent of the original-oil-in-place while partially upgrading the crude oil in situ. Petrobank controls all intellectual property rights to the Thai process and related enhancements, including the patented Capri technology, which offers the potential for further in situ upgrading through the use of a wellbore integrated catalyst.
Thai has many potential benefits over other in situ recovery methods, such as SAGD (steam-assisted gravity drainage). These benefits include higher resource recovery, lower production and capital costs, minimal usage of natural gas and fresh water, a partially upgraded crude oil product, reduced diluent requirements for transportation, and lower greenhouse gas emissions. The Thai process also has the potential to operate in lower-pressure, lower-quality, thinner and deeper reservoirs than current steam-based recovery processes.
Thai can also be applied to other heavy oil deposits and it is the company's strategy to initiate projects in mobile oil reservoirs in Canada and/or internationally. The ultimate goal is to capture a global portfolio of heavy oil resources where the application of the Thai technology can lead to greatly improved recovery rates and significant long-term value growth for the company. In support of this activity, Petrobank's subsidiary, Petrominerales Ltd. (TSX: PMG), is evaluating two large heavy oil technical evaluation areas in Colombia covering 1.1 million acres for the potential application of Thai.
FoxV wrote:Thanks Father' I was curious about how the Thai trial was coming.
I also didn't realize there were so many reputed benefits to the process.
Do you have any idea about what the reality might be?
Air injection and combustion was initiated on the first of the three project wells on July 20, 2006, and we have been continually injecting air into the vertical well of this center well pair. During the first three weeks of air injection, in-situ combustion ignition was confirmed as we measured various indicators of the combustion reaction, including significantly rising temperatures in the reservoir zone, production of combustion gases and rising horizontal well bore temperatures. This trend continued through the third quarter with recorded reservoir temperatures reaching as high as 800 degrees Centigrade. Combustion gas analysis consistently demonstrated a high ratio of carbon dioxide to carbon monoxide, indicating a very high level of conversion of oxygen, hydrocarbon gases indicative of thermocracking of oil in-situ, and free hydrogen generated from high temperature reactions, all indicators of efficient high temperature combustion. These data also suggest that we are upgrading the oil in-situ. We are very early in the process of building out the combustion front in the first THAI™ well pair and estimate that only approximately 7,000 m3 of the reservoir has been affected by combustion at the toe of the horizontal well, which is less than one percent to total reservoir volume expected to be affected by combustion over the life of each THAI™ well pair.
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