Wellbore mechanical integrity for in situ pyrolysis

A method of completing a wellbore in a subsurface formation, the subsurface formation comprising organic-rich rock that is to be heated in situ so as to pyrolyze solid hydrocarbons into hydrocarbon fluids, and the method comprising:

• forming a wellbore at least partially through the subsurface formation;
• identifying zones within the subsurface formation and along the wellbore to experience temperatures in excess of a pyrolysis temperature;
• identifying sections along the wellbore where an organic richness of formation rock within the identified zones varies over short distances so as to present a risk of mechanical failure to downhole equipment, wherein identifying sections comprises locating sections along the wellbore where a Fischer Assay oil content of the formation rock adjacent the wellbore vertically averaged over a selected interval changes by more than about 10 gallons per ton within a vertical span of five feet or less;
• and
• selectively mechanically strengthening the downhole equipment in at least one of the identified sections to withstand a thermally-induced stress caused by pyrolyzing solid hydrocarbons,
• wherein selectively mechanically strengthening the downhole equipment comprises at least one of (i) increasing a cross-sectional thickness of the downhole equipment over the cross-sectional thickness of the downhole equipment within one or more non-identified sections and (ii) employing downhole equipment with higher strength metallurgy over downhole equipment within one or more non-identified sections.