Miscellaneous Subsurface Methods 



729 



of the field. The well would produce more oil if desired, the exact amount 

 of which is unknown. 



Wells E and F in figure 390, being respectively in the Strawn sand in 

 the Wichita Falls, Texas, area and in the Pennsylvanian sand in the New 

 Hope field of Oklahoma, both give further information with regard to the 

 shape of the pressure curves during the course of treatment. The break in 

 pressure as in well E may often show no increase in production. This fact 

 is probably due to breaking into a weak interval, such as a shale zone or 



WELL E 



STRAWN SAND 



WICHITA FALLS, TEXAS 



-STARTING FRACTURE 



PRESSURE CURVE 



PUMRNG GEL IN TUBING 

 FORCING OIL INTO FORMATION 

 - I TRUCK ^- 



^ CLOSED IN PRESSURE 



WELL F 

 PENNSYLVANIA SAND 

 NEW HOPE FIELD, OKLA. 



CLOSED IN PRESSURE 



Figure 390. Pressure and volume of injection changes during Hydrafrac treatment. 



some other nonproductive part of the section being treated. In the case 

 of well E, the production before and after treatment was 12 BOPD in each 

 case. Well F, on the other hand, shows a typical curve of fracture exten- 

 sion with even a slight rise in pressure occurring after the gel was in the 

 formation for a short distance, and then a gradual tapering off, in spite 

 of injection at high volumes. Curves of this type have appeared on a large 

 percent of the treated wells which were helped. 



