Patent ID: 6591908
Filing Date: 2003-07-15
Classification: C09K,E21B

Abstract:
A predominantly water-based thermal method for producing hydrocarbons from a subterranean formation having indigenous hydrocarbons, at least one producing means that can communicate with at least a portion of the formation, at least one injection means comprising a wellbore, and a mixing zone in a near-wellbore region of the wellbore, the method comprising:(a) selecting a first component, W, and a second component, S, wherein component W is selected from steam, hot water and combinations thereof, and component S is a solvent selected from C1 to C30 hydrocarbons, carbon dioxide, carbon monoxide and combinations thereof; (b) introducing at least component W and component S into the at least one injection means; (c) preparing a heated water-based injection fluid composition before, in or after the at least one injection means, the heated water-based injection fluid composition comprising at least component W and component S in a W to S volume ratio, defined by: (W&it;:&it;S)n=(volume&it;â€ƒ&it;of&it;â€ƒ&it;component&it;â€ƒ&it;W&it;â€ƒ&it;injected&it;â€ƒ&it;inan&it;â€ƒ&it;injection&it;â€ƒ&it;sequencing&it;â€ƒ&it;interval&it;â€ƒ&it;n)(volume&it;â€ƒ&it;of&it;â€ƒ&it;component&it;â€ƒ&it;S&it;â€ƒ&it;injected&it;â€ƒ&it;inan&it;â€ƒ&it;injection&it;â€ƒ&it;sequencing&it;â€ƒ&it;interval&it;â€ƒ&it;n)&it;â€ƒâ€ƒwhere the total number of injection sequencing intervals is in a range from about 2 to about 12,000, â€ƒwherein the heated water-based injection fluid composition has a first W to S volume ratio, (W:S)1, greater than about 5:1 and the volume of component S injected in the first injection sequencing interval, where n=1, is greater than 0; (d) changing the ratio, at least once, from (W:S)1 to a different W to S volume ratio, (W:S)n, wherein at least one (W:S)n than (W:S)1 and each (W:S)n is greater than or equal to about 1.5:1; and (e) collecting at least a portion of the indigenous hydrocarbons using the at least one producing means.