At approximately 1230 Central time, the airplane was substantially damaged during a forced landing following a reported loss of engine power while maneuvering near Olney, Texas. The Commercial pilot, sole occupant of the airplane, sustained minor injuries. Visual conditions prevailed for the pipeline patrol mission. The pilot later reported he noticed that the throttle had backed out and pushed it full forward. As the airspeed decayed, he applied carburetor heat and noticed the engine wasnt running rough. The pilot pushed the carburetor heat back in, and noted that the engine was still losing power. At an altitude of approximately 200 feet above ground level, the pilot initiated a forced landing to a nearby field. During the landing roll, the nose gear dug into terrain and the airplane nosed over.The airplane came to rest inverted within an open field; fuel was observed leaking from both fuel caps and was observed within both fuel tanks.