John Ivory

Experimental and Economic Analysis of the Thermal Solvent and Hybrid Solvent Processes

Several partially scaled laboratory model experiments were conducted to evaluate a hybrid solvent-steam process for recovery of heavy oil or bitumen. All experiments used Athabasca UTF bitumen, and modelled a 30-metre-thick formation. The experiments were compared using a common set of economic assumptions. The experiments showed that a hybrid solvent-steam process could recover bitumen at steam-oil ratios much lower than those observed for steam assisted gravity drainage (SAGD), and achieve reasonable ultimate oil recovery (60% IOIP). The economic analysis based on experiments indicated that a hybrid solvent-steam process could be more cost-effective than SAGD for a 30-m Athabasca formation.

Preliminary considerations on application of steamflooding in a toe-to-heel configuration

With the advent of horizontal wells, a distinct change is tacitly taking place in our approach to the improved recovery of heavy oil-from displacing mobilized oil in a flood pattern from injector to producers over long distances on the order of hundreds of metres to short-distance oil displacement (SDOD) processes (typically over a few tens of metres). SDOD processes comprise Steam Assisted Gravity Drainage (SAGD), Cyclic Steam Stimulation (CSS) and Toe-to-Heel (TTH) Displacement Processes, which comprise Toe-to-Heel Air Injection (THAI), with its variant catalytic THAI (CAPRI), and Toe-to-Heel Waterflooding (TTHW). Presently SAGD is commercially used, while THAI has been under field testing for 3 years; testing of CAPRI is scheduled to start in 2010. TTHW has been under field testing both in the US and Canada for more than 4 years. Steamflooding in a TTH configuration (TTH steamflooding) uses vertical wells as injectors and horizontal wells as producers, arranged in a staggered line drive, with producers having their toes close to the shoes of vertical injectors; the horizontal section of producers is located at the base of the pay. The vertical wells are used for initiating the steam front, which subsequently is anchored at the toe of the horizontal producer; it is then propagated towards the producers heel. In TTH steamflooding, the existing deficiency of conventional steamflooding schemes in terms of low vertical sweep is overcome by the beneficial use of gravity. To investigate the potential of TTH steamflooding, some laboratory tests were conducted. The objective was to assess the feasibility of TTH steam and thermo-solvent flooding (steam+propane co-injection) by carrying out 3D model experiments using heavy oil with a viscosity of 15,000 cP. Laboratory results showed that the concepts of TTH steamflooding and TTH steamflooding with solvent are feasible. All in all, stability of TTH steamflooding was relatively good, while the stability of TTH steamflooding with the addition of nitrogen or propane was much better. Significant improvements in design and operation of these processes were needed in order to promote override during the early phase, and obtain a stable and efficient process. The improvements included a cold (gas fingering) and a hot (steam-based) communication phase-, and controlling lateral spread of steam by using two additional vertical control wells (positioned laterally but close to the heel of the horizontal producer) for conducting a limited steamflood. Nitrogen was injected along with steam in the conventional steamflood; propane replaced nitrogen in TTH steamflooding with solvent. With these improvements, rise of steam chamber to the top occurred much earlier, and a favourable tilt-forward-angle of the thermal front was quickly obtained. TTH steamflooding with solvent proved superior to the TTH steamflooding, as the channeling of steam through the horizontal well was much better controlled, and the oil recovery was considerably faster. With these improvements, the oil recovery increased from 50 - 54% to 75 - 77%, and the operation became smoother. Presently, the process can be considered only for reservoirs where oil has some mobility under reservoir conditions. In order to develop the full potential of TTH steamflooding, technology means are needed for controlling channeling through the horizontal producer (this control Occurs naturally in the THAI process); at present there are a few methods which seem promising.

Hollow fiber and spiral wound contactors for fluid/particle contact and interaction

The unit operations of fluid/particle contact and interaction are the basis of many chemical processing operations. The mass transfer rate and pressure drop in the contactor are critical to the process performance. Hollow fiber and spiral wound contactors, which are derived frommodule development in membrane separation technology, have been recently developed as an alternative to the conventional design of fluid/particle contactors. These novel contactors allow the use of minute particles to enhance mass transfer without giving rise to a high pressure drop and can be used to carry out adsorption separation or catalytic reaction. In this paper, therecent developments in this area are reviewed, and some outstanding issues yet to be solved are highlighted. Though there are some preliminary proof-of-concept studies, further investigations are required to establish the relationships between the contactor design parameters, the process variables, and the process performance. Continued efforts are needed to identify the specific niche applications for the new contactor technology.