wellbore 12 may be accomplished by positioning the sensor transmitters 56 at different depths in the formation 14 such as by drilling the wellbores 36 44 70 72 at different depths or positioning the sensor transmitters 56 at different depths in their respective wellbores referring additionally now to fig4 another method 80 embodying principles of the present invention is representatively and schematically illustrated in the method 80 a main wellbore 82 is drilled into a formation 84 the wellbore 82 may extend generally horizontally in the formation 84 as depicted in fig4 but such is not necessary in keeping with the principles of the present invention fractures 86 88 are formed extending outward from the wellbore 82 into the formation 84 alternatively the fractures 86 88 may be portions of a single fracture extending outward from the wellbore 82 another wellbore 90 is drilled into the formation 84 so that it intersects the fracture 88 preferably the wellbore 90 intersects the fracture at an angle other than ninety degrees a plug 92 is installed in the wellbore 90 to prevent fluid flow from the formation 84 upwardly through the wellbore 90 a branch or lateral wellbore 94 is drilled outward from the parent wellbore 90 the wellbore 94 is drilled into.