As a kind of methodology to develop coalbed methane in China, RMRS (Rotating Magnet Ranging System) has been popular in SAGD operation in recent years. In Liaohe Oilfield SAGD (Steam Assisted Gravity Drainage) is becoming a more and more mature methodology. In a pair of parallel wells high pressure steam is injected into a horizontal well to drain heavy oil into the lower production well. However, not all thermal resources have not been exploited, such as heat of the hot production fluid, flue gas and hot brine separated by the steam-water separator in the boiler.

Trials and researches were finalized on many dual-horizontal wells in Liaohe Oilfield to learn about the present situation and technical capabilities, while thermodynamic models of various types were established and experimental means were applied to analyze thermal distribution and each of the thermal sources previously mentioned. Effects of various media, flow rates and temperatures on thermal utilization and heat deficit rates were studied on the assumption that one ton crude oil was produced per hour.

Waste heat of flue gas may be utilized to help combust air and the thermo-coil may be used as the air preheater, which improves boiler’s heat efficiency. The high temperature production fluid may be used to heat water in the boiler first and then used as the heat source of the absorption heat pump, so that heat is transferred from the low temperature heat source to the high temperature heat source and the low grade heat energy is recycled. As a high grade waste heat, the HPHT brine that is separated from moist steam in the boiler takes up twenty percent of the total water and shall not be only used to heat injected water. Instead, it may be used to achieve flash evaporation. Thus, waste water is heated and distilled water is recycled.

The waste heat recyling model applies thermo-coil air preheaters to recycle flue gas and flash evaporated hot brine to evaporate waste water. Beside, hot production fluid is recycled to heat boiler water. On a basis of the same fuel consumption volume, the recovery rate and marketability of crude oil are both improved.

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