Abstract: This invention provides a method for treating multiple intervals in a wellbore by perforating at least one interval then treating and isolating the perforated interval(s) without removing the perforating device from the wellbore during the treatment or isolation. The invention can be applied to hydraulic fracturing with or without proppant materials as well as to chemical stimulation treatments.

Abstract: The invention relates to a method for forming a welded joint between abutting pieces of steel. The welded joint is produced by first forming a strength weld and then depositing additional weld metal on the toe of the strength weld to form a toughness weld. The fusion interface of the toughness weld forms a minimum angle with the direction of the maximum tensile load across the welded joint. The toughness weld toe is separated from the heat-affected zone of the strength weld to effectively prevent propagation of a crack initiated at the toughness weld toe into the heat-affected zone of the strength weld. The welded joint so produced is substantially resistant to failure by brittle fracture.

Abstract: The invention provides an apparatus and method for perforating and treating multiple intervals of one or more subterranean formations intersected by a wellbore by deploying a bottom-hole assembly (“BHA”) having a perforating device and at least one sealing mechanism within said wellbore. The BHA may be deployed in the wellbore using a tubing string or cable; or alternatively, the BHA may be deployed using a tractor system attached directly to the BHA. The perforating device is used to perforate the first interval to be treated. Then the BHA is positioned within the wellbore such that the sealing mechanism, when actuated, establishes a hydraulic seal in the wellbore to positively force fluid to enter the perforations corresponding to the first interval to be treated. A treating fluid is then pumped down the wellbore and into the perforations created in the perforated interval.