Compositions and methods of using same in producing heavy oil and bitumen
Compositions and methods of using same are described for negating asphaltene deposition in a formation, wellbore, near wellbore region, and production tubing. Compositions of the invention comprise an asphaltene solvent and a viscosity reducing agent, the asphaltene solvent and viscosity reducing agent present in a ratio so as to substantially reduce viscosity of an asphaltene-containing material while substantially negating deposition of asphaltenes either in a reservoir, in production tubing, or both when mixed or otherwise contacting the asphaltene-containing material. Methods of the invention comprise forcing a composition comprising an asphaltene solvent and a viscosity reducing agent to contact an asphaltene-containing hydrocarbon in an underground geologic formation, and producing from the formation a production composition comprising at least some of the treatment composition and at least some of the asphaltene-containing hydrocarbon under conditions sufficient to substantially negate deposition of asphaltenes in the formation.
1. A method comprising forcing a treatment composition comprising an asphaltene solvent and a viscosity reducing agent to contact an asphaltene-containing hydrocarbon in an underground geologic formation, and producing from the formation a production composition comprising at least some of the treatment composition and at least some of the asphaltene-containing hydrocarbon under conditions sufficient to substantially negate deposition of asphaltenes in the formation, wherein the forcing and producing steps are combined with an integrated steam assisted gravity drainage (SAGD) and surface upgrading process, combusting at least some of the asphaltenes to produce hydrogen that is later used in hydrocracking of bitumen into gas oils, or used as fuel gas in producing steam for the SAGD part of the integrated process.
2. The method of claim 1 , comprising preparing the treatment composition on-site, either at the surface or downhole, using suitable mixing equipment.
3. The method of claim 2 , comprising heating or cooling, and/or changing pressure during mixing and/or during application, of the treatment composition or the formation.
4. The method of claim 1 , wherein the conditions sufficient to avoid substantial deposition of asphaltenes may comprise adjusting the temperature of the treatment composition, the formation, or both to temperatures ranging from 0° C. to 200° C., adjusting the pressure of the formation, the treatment composition, or both to pressure ranging from about 1 to about 10 MPa, and adjusting the molar ratio of asphaltene solvent to viscosity reducing agent from between about 10:1 to about 1:10.
5. The method of claim 1 , comprising forcing the treatment composition into one or more injection wellbores, and producing the production composition from one or more production wellbores.
6. The method of claim 1 , comprising forcing the treatment composition and producing the production composition from the same wellbore.
7. The method of claim 1 , comprising reducing pressure of the production composition, optionally with application of heat, to separate and recover at least a portion of the treatment composition, and recycling the treatment composition.