Stimulation by explosives. Pt. 2. Powerful borehole slurry passes field tests

The most powerful commercially available explosive is used in a versatile and safe slurry form to release high energy in the well bore. Sustained 200 bpd increases from explosive fracturing have occurred in field tests by The Western Co. in producing oil wells. The key features of the method are wellbore loading with bagged or high viscosity explosive, and solid tamping with cement and gravel. Some advantages of the system include the following: (1) good explosive-to-formation contact gives maximum energy transfer; (2) high stresses near the well bore cause desirable random fracturing; (3) concentrated explosive generates the highest volume of gases for fracture; (4) casing is not damaged with protective tamping; and (5) cost compares with hydraulic fracturing. Field results have been obtained from test site quarry shots, dry- hole tests, and oil wells to depths of 7,000 ft, as shown by tabular data. Treatment size in producing wells in both cased and open hole has generally been over 1,000 lb per well with large shots up to 8,500 lb. Poor tests in some wells point out the fact that explosive fracturing is not suitable for all wells.