Importance

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Abstract

This invention describes a method of stimulating production from an oil well by removing solid wax deposits from a production zone. An electrical resistance heater comprised of a packed bed of spherical heating elements is lowered through the tubing on a wireline and placed adjacent to the perforations. Solvent is pumped through the heater to raise its temperature by 200.degree. C. and then into the formation to contact wax deposits. The solid wax deposits are liquified and together with the oil and the solvent form a single liquid phase. The wax is then removed from the formation by placing the well back on production. Because the invention completely avoids the use of either water or gas, the saturation of the water and gas phases in the formation is minimized, thereby maximizing the mobility of the liquid phase containing the wax and facilitating the removal of the liquified wax from the treatment area before it reprecipitates. The packed bed heater has a large surface area and a large heat transfer coefficient, so high power rates (150 kW) can be achieved within a compact volume (6 m long .times. 5 cm id) without solvent degradation. By heating the solvent to a high temperature, a minimum volume of solvent is required, thereby minimizing production downtime and solvent costs. The burnout and catastrophic failure problem usually associated with resistive heaters is avoided due to the multiplicity of current paths through the packed bed.

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First Claim