Conventional EOR methods like steam-injection are usually not cost effective for deep wells and wells producing from thin pay zones, due to excessive heat loss to the overburden. For such wells minimizing heat losses can be achieved by using microwave heating assisted gravity drainage. In this study, the feasibility of this method was investigated. Heavy oil samples from conceptual reservoirs (Bati Raman (9.5 API), Garzan (12 API) and Camurlu (18 API)) in south east Turkey were used. Using a novel graphite core holder packed with crushed limestone premixed with crude oil and water effects of operational parameters like heating time and waiting period as well as rock and fluid properties like porosity, permeability, wettability, salinity, and initial water saturation were studied.
Crude oils whose API gravity smaller than 20 are called heavy oil that can be produced by using thermal recovery techniques. In these techniques, heat is injected into the formation, which reduces the oil's viscosity and results in a higher production rate (Conaway, 1999). Hot-fluid injection, in-situ combustion and thermal stimulation are the thermal recovery methods (Prats, 1982). Microwave heating is a thermal stimulation method and in the past microwave radiation has been used in many areas of the petroleum industry (Bjorndalen and Islam, 2004). Microwave irradiation applications include inspecting coiled tubing and line pipe (Stanley, 2001), as a treatment of waste-water/oil emulsion (Vega et al, 2002) and for saturation monitoring (Honarpour et al, 1996). Microwaves are also used for monitoring phase behavior and measuring multiphase flow (Rogers et al, 1988; Ashton et al, 1994). Furthermore, microwaves are used in various technological and scientific fields in order to heat dielectric and, on occasions, non-dielectric materials (Haque, 1999; Zlotorzynski, 1995). Thus, processes such as the drying and heating of minerals and inorganic products, the carbothermic reduction of metal oxides, mineral leaching, coal liquefaction, the production of active carbon, spent carbon regeneration and the surface chemistry modification of carbons are only a few examples of the different processes currently being used or investigated (Bradshaw et al, 1999, Andres et al, 1998). Microwave heating has also been considered as an alternative for carrying out the pyrolysis of biomass (Miura et al, 2000; Kriegerbrockett, 1994), coal (Monsef-Mirzai et al, 1992; 1995), oil shales (El Harfi et al, 2000; Chanaa et al, 1994), and various organic wastes (Holland, 1992; 1995). These materials are, in general, poor receptors of microwave energy, so they cannot be heated directly up to the high temperatures usually required to achieve total pyrolysis. However, microwave-induced pyrolysis is possible, if the raw material is mixed with an effective receptor of microwave energy such as carbon (El Harfi et al, 2000; Abernethy, 1976) or certain metal oxides (Monsef-Mirzai et al, 1992; 1995). Microwave heating effectiveness depends on several parameters; such as heating period, amount and type of matter that will be subjected to the microwave irradiation, the cell material that the matter will be placed in (Datta and Anantheswaran, 2001).