A method for in-situ remediation and recovery of a tar mat TM layer of a sub-surface formation can include deasphalting oil obtained from an oil column to produce a deasphalted oil, extracting an aromatic solvent from the deasphalted oil to provide a residual deasphalted oil and an extracted solvent; and injecting the residual deasphalted oil and the extracted solvent into the tar mat TM layer of the sub-surface formation using at least one horizontal well selected from the group consisting of a single horizontal well, two parallel horizontal wells, and a plurality of horizontal wells arranged in a radial configuration.