The MPas formation packer has an elastomeric element with composite structure which is set mechanically by shifting a balance sleeve allowing wellbore hydrostatic pressure to act against an atmospheric chamber and apply setting force to the non-inflatable element. The element is then mechanically locked eliminating the requirement of the wellbore fluid to maintain the set. Wellbore hydrostatic pressure will continue to apply a setting force on the element throughout the life of the packer which will compensate for movement of the formation and will allow for additional setting force to be applied at any time. Additional setting force can be attained by applying additional pressure with a cup tool or by applying pressure to the entire casing string if applicable. The MPas packer is normally run in the liner string between screens, slotted casing, or gravel packed sections as a means to isolate production intervals. It can also be used to isolate the openhole/liner annulus in openhole completions in conjunction with stage cementing equipment. The MPas packer can be run as a single or stacked in multiples to provide increased seal length.