Fracturing, explosive

A winchester of fuming nitric acid with a plastics cap burst, probably owing to internal pressure build-up and uneven wall thickness. The explosion fractured... 

Explosive Di sintegrotion, Explosive Fracturing or Explosive Shattering. (See also Explosive Unit Operations)... 

History-Explosive Fracturing for Well Stimulation", ProeSpring Meeting Mid-Continent District, Div-Production, API, Wichita, Kansas, April 8-10, 1970, pp 58-63 2)G.Cohn, Edit, Expls Pyrots 5(6), 1972 (Abstract)... 

In the first two tests of a series of three explosive fracturing experiments, well 3 was used to inject and displace 100 and 300 qt of NG1 in the depth intervals from 70 to 74 ft. Continuous sampling of surrounding... 

Results. The first explosive fracturing test detonated 100 qt of NG1 displaced into the formation from well 3 at a depth interval from 70 to 74 ft. Following detonations in wells 3 and 4, fracture intervals in the wellbores connecting the injection well 3 and other wells were determined by airflow measuerments. 

Comparing these airflow intervals with those permeable zones induced by conventional hydraulic fracturing indicated that explosive fracturing created additional communication paths to wells 2 and 5 at the 73-ft level. However, the injection capacity of well 3 was reduced 64%. This may have resulted from too wide a dispersion of the liquid explosive, so that the shot was not strong enough to lift and fracture the overburden rock permanently, or the fractures may have been plugged by fine oil-shale particles or mud. 

Void volume based on the elevation-change contours and the area enclosed by the dashed line in Figure 3 was calculated to be nearly 150 cu ft. The total area affected by explosive fracturing could not be determined because of the lack of elevation-measuring stations outside of the contoured area. 

In general, hydraulic fracturing with sand propping provided adequate void space for emplacement of the NG1 in these explosive-fracturing tests in the oil shale. Explosive fracturing caused significant increases in fracture permeability when a sufficient NG1 charge was detonated. 

Results from a subsequent in situ combustion experiment on this site (18), to produce shale oil from oil shale, indicated that combustion could be sustained in an explosively fractured zone. 

Two shots (E-E, F-F) using a total of 536 lbs of TNT were detonated in wells 3 and 4 between depths of 71 and 87 ft. After cleanout in wells 1 and 2, 150-lb charges of TNT were placed in each hole to depths of 85 and 83 ft, respectively, and detonated (shot J-J). Wells 2 and 4 were cleaned out, and a total of 250 lb of TNT filled the holes to depths of 76 and 77 ft, respectively, and were detonated (shot L-L). Wells 1 and 3 were prepared for reshooting by charging 150 lb of TNT in each wellbore at depths of 77 and 74 ft, respectively, and were detonated (shot M-M). This explosive fracturing series was concluded by loading... 

Purpose. This fracturing program was intended to devise an effective method to fracture the formation with wellbore shots. More specifically, Green River site 1 was developed to test chemical explosive fracturing procedures for establishing communication between wells at greater depths and well spacings than had been previously attempted in oil shale. 

The completed site contained 10 pattern wells for explosive-fracturing research. Six wells were drilled on 50-ft spacing to form a rectangle with three wells on a side. The remaining four wells were drilled on 25-ft spacing to form a five-spot pattern (Figure 6). All wells were completed similarly to the earlier described test wells. 

The final explosive-fracturing test performed on this site was a simultaneous shot detonated in the wells of the five-spot pattern. Wire-line measurements were obtained to determine total depth, and caliper logs were run to determine wellbore enlargement from which to calculate the amount of TNT to fill each well. Water was swabbed and bailed... 

Results of explosive fracturing tests in oil shale show that NG1 will detonate and that the explosion will propagate in water-filled natural fractures and sand-propped, hydraulically induced fractures in oil shale. The shale was fragmented by this method, and a successful underground retorting experiment to recover shale oil was performed. 

A winchester of fuming nitric acid with a plastics cap burst, probably owing to internal pressure build-up and uneven wall thickness. The explosion fractured an adjacent bottle of acetone which ignited on contact with the oxidant [1]. Segregation of oxidants and fuels in storage is essential to prevent such incidents, which have occurred previously elsewhere. Another explosion resulted, when attempting to clear a jammed glass stopper by successive application of acetone and nitric acid [2],... 

Computer simulation of explosive fracture of rock can be carried out with finite difference stress wave propagation codes, such as the YAQUI code (2). YAQUI integrates in time the coupled partial differential equations for the conservation of mass, momentum, and energy. For a compressible fluid, these equations are... 

The steps in assembling the computational tools needed to simulate the explosive fracture of oil shale have been described. The resulting code, with its input data, was then used to simulate three explosive field experiments. The results of the calculations are in good agreement with what actually occurred in the field. Further detailed comparisons are in progress for these experiments and the others that have been conducted. As this is done, improvements will be made in the input data and in the code physics. 

Explosive fracturing devices used to fracture rock formations at the base or shaft walls of oil wells to increase the flow of gas or oil. These devices may use shaped charges or oil well cartridges syn, industrial ammunition) which propel steel or hardened projectiles. 

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