Heating An Organic-Rich Rock Formation In Situ To Produce Products With Improved Properties

Abstract

A method of producing hydrocarbon fluids with improved hydrocarbon compound properties from a subsurface organic-rich rock formation, such as an oil shale formation, is provided. The method may include the step of heating the organic-rich rock formation in situ. In accordance with the method, the heating of the organic-rich rock formation may pyrolyze at least a portion of the formation hydrocarbons, for example kerogen, to create hydrocarbon fluids. Thereafter, the hydrocarbon fluids may be produced from the formation. Hydrocarbon fluids with improved hydrocarbon compound properties are also provided.

1 . An in situ method of producing hydrocarbon fluids from an organic-rich rock formation, comprising:
 a) heating in situ a section of an organic-rich rock formation containing formation hydrocarbons, the section of the organic-rich rock formation having a lithostatic stress;   b) pyrolyzing at least a portion of the formation hydrocarbons thereby forming a hydrocarbon fluid; and   c) producing the hydrocarbon fluid from the organic-rich rock formation, the produced hydrocarbon fluid comprising a condensable hydrocarbon portion, the condensable hydrocarbon portion having:
 i) one or more of a n-C6 to benzene weight ratio less than 35.0, a n-C7 to toluene weight ratio less than 7.0, a n-C8 to ethylbenzene weight ratio less than 16.0, a n-C8 to ortho-xylene weight ratio less than 7.0, a n-C8 to meta-xylene weight ratio less than 1.9, a n-C9 to 1-ethyl-3-methylbenzene weight ratio less than 8.2, a n-C9 to 1-ethyl-4-methylbenzene weight ratio less than 4.4, a n-C9 to 1,2,4-trimethylbenzene weight ratio less than 2.7, a n-C10 to 1-ethyl-2,3-dimethylbenzene weight ratio less than 13.5, a n-C10 to tetralin weight ratio less than 25.0, a n-C12 to 2-methylnaphthalene weight ratio less than 4.9, and a n-C12 to 1-methylnaphthalene weight ratio less than 6.9; 
 ii) one or more of a n-C9 to IP-9 weight ratio greater than 2.4, a n-C10 to IP-10 weight ratio greater than 1.4, a n-C11 to IP-11 weight ratio greater than 1.0, a n-C13 to IP-13 weight ratio greater than 1.1, a n-C14 to IP-14 weight ratio greater than 1.1, a n-C15 to IP-15 weight ratio greater than 1.0, a n-C16 to IP-16 weight ratio greater than 0.8, a n-C18 to IP-18 weight ratio greater than 1.0, and a n-C19 to pristane weight ratio greater than 1.6; 
 iii) one or more of a n-C7 to cis 1,3-dimethyl cyclopentane weight ratio less than 13.1, a n-C7 to trans 1,3-dimethyl cyclopentane weight ratio less than 14.9, a n-C7 to trans 1,2-dimethyl cyclopentane weight ratio less than 7.0, a n-C7 to methyl cyclohexane weight ratio less than 5.2, a n-C7 to ethyl cyclopentane weight ratio less than 11.3, a n-C8 to 1,1-dimethyl cyclohexane weight ratio less than 16.0, a n-C8 to trans 1,2-dimethyl cyclohexane weight ratio less than 17.5, and a n-C8 to ethyl cyclohexane weight ratio less than 12.3; 
 iv) one or more of a total C10 to total C20 weight ratio greater than 2.8, a total C11 to total C20 weight ratio greater than 2.3, a total C12 to total C20 weight ratio greater than 2.3, a total C13 to total C20 weight ratio greater than 2.9, a total C14 to total C20 weight ratio greater than 2.2, a total C15 to total C20 weight ratio greater than 2.2, and a total C16 to total C20 weight ratio greater than 1.6; 
 v) one or more of a total C10 to total C25 weight ratio greater than 7.5, a total C11 to total C25 weight ratio greater than 6.5, a total C12 to total C25 weight ratio greater than 6.5, a total C13 to total C25 weight ratio greater than 8.0, a total C14 to total C25 weight ratio greater than 6.0, a total C15 to total C25 weight ratio greater than 6.0, a total C16 to total C25 weight ratio greater than 4.5, a total C17 to total C25 weight ratio greater than 4.8, and a total C18 to total C25 weight ratio greater than 4.5; 
 vi) one or more of a total C7 to total C29 weight ratio greater than 3.5, a total C8 to total C29 weight ratio greater than 9.0, a total C9 to total C29 weight ratio greater than 12.0, a total C10 to total C29 weight ratio greater than 15.0, a total C11 to total C29 weight ratio greater than 13.0, a total C12 to total C29 weight ratio greater than 12.5, a total C13 to total C29 weight ratio greater than 16.0, a total C14 to total C29 weight ratio greater than 12.0, a total C15 to total C29 weight ratio greater than 12.0, a total C16 to total C29 weight ratio greater than 9.0, a total C17 to total C29 weight ratio greater than 10.0, a total C18 to total C29 weight ratio greater than 8.8, a total C19 to total C29 weight ratio greater than 7.0, a total C20 to total C29 weight ratio greater than 6.0, a total C21 to total C29 weight ratio greater than 5.5, and a total C22 to total C29 weight ratio greater than 4.2; 
 vii) one or more of a normal-C7 to normal-C20 weight ratio greater than 0.9, a normal-C8 to normal-C20 weight ratio greater than 2.0, a normal-C9 to normal-C20 weight ratio greater than 1.9, a normal-C10 to normal-C20 weight ratio greater than 2.2, a normal-C11 to normal-C20 weight ratio greater than 1.9, a normal-C12 to normal-C20 weight ratio greater than 1.9, a normal-C13 to normal-C20 weight ratio greater than 2.3, a normal-C14 to normal-C20 weight ratio greater than 1.8, a normal-C15 to normal-C20 weight ratio greater than 1.8, and normal-C16 to normal-C20 weight ratio greater than 1.3; 
 viii) one or more of a normal-C10 to normal-C25 weight ratio greater than 4.4, a normal-C11 to normal-C25 weight ratio greater than 3.8, a normal-C12 to normal-C25 weight ratio greater than 3.7, a normal-C13 to normal-C25 weight ratio greater than 4.7, a normal-C14 to normal-C25 weight ratio greater than 3.7, a normal-C15 to normal-C25 weight ratio greater than 3.7, a normal-C16 to normal-C25 weight ratio greater than 2.5, a normal-C17 to normal-C25 weight ratio greater than 3.0, and a normal-C18 to normal-C25 weight ratio greater than 3.4; 
 ix) one or more of a normal-C7 to normal-C29 weight ratio greater than 18.0, a normal-C8 to normal-C29 weight ratio greater than 16.0, a normal-C9 to normal-C29 weight ratio greater than 14.0, a normal-C10 to normal-C29 weight ratio greater than 14.0, a normal-C11 to normal-C29 weight ratio greater than 13.0, a normal-C12 to normal-C29 weight ratio greater than 11.0, a normal-C13 to normal-C29 weight ratio greater than 10.0, a normal-C14 to normal-C29 weight ratio greater than 9.0, a normal-C15 to normal-C29 weight ratio greater than 8.0, a normal-C16 to normal-C29 weight ratio greater than 8.0, a normal-C17 to normal-C29 weight ratio greater than 6.0, a normal-C18 to normal-C29 weight ratio greater than 6.0, a normal-C19 to normal-C29 weight ratio greater than 5.0, a normal-C20 to normal-C29 weight ratio greater than 4.0, a normal-C21 to normal-C29 weight ratio greater than 3.6, and a normal-C22 to normal-C29 weight ratio greater than 2.8; or 
 x) one or more of a normal-C10 to total C10 weight ratio less than 0.31, a normal-C11 to total C11 weight ratio less than 0.32, a normal-C12 to total C12 weight ratio less than 0.29, a normal-C13 to total C13 weight ratio less than 0.28, a normal-C14 to total C14 weight ratio less than 0.31, a normal-C15 to total C15 weight ratio less than 0.27, a normal-C16 to total C16 weight ratio less than 0.31, a normal-C17 to total C17 weight ratio less than 0.31, a normal-C18 to total C18 weight ratio less than 0.37, normal-C19 to total C19 weight ratio less than 0.37, a normal-C20 to total C20 weight ratio less than 0.37, a normal-C21 to total C21 weight ratio less than 0.37, a normal-C22 to total C22 weight ratio less than 0.38, normal-C23 to total C23 weight ratio less than 0.43, a normal-C24 to total C24 weight ratio less than 0.48, and a normal-C25 to total C25 weight ratio less than 0.53. 
   
     
     
         2 . The method of  claim 1 , wherein the organic-rich rock formation is an oil shale formation. 
     
     
         3 . The method of  claim 1  further comprising the step of selecting a pillar geometry to alter the lithostatic stress of the section of the organic-rich rock formation. 
     
     
         4 . The method of  claim 3  wherein the altered lithostatic stress is greater than 200 psi. 
     
     
         5 . The method of  claim 1  further comprising the step of selecting a pillar location to alter the lithostatic stress of the section of the organic-rich rock formation. 
     
     
         6 . The method of  claim 5  wherein the altered lithostatic stress is greater than 200 psi. 
     
     
         7 . The method of  claim 1  further comprising the step of selecting a heating and pyrolysis formation region thickness to alter the lithostatic stress of the section of the organic-rich rock formation. 
     
     
         8 . The method of  claim 7  wherein the altered lithostatic stress is greater than 200 psi. 
     
     
         9 . The method of  claim 1  further comprising the step of selecting a heating sequence to alter the lithostatic stress of the section of the organic-rich rock formation. 
     
     
         10 . The method of  claim 9  wherein the altered lithostatic stress is greater than 200 psi.