Discussion about efficiency increasing for hydraulic jet nozzle

Through analyzing 38 sets of nozzle failure during hydraulic jet fracturing, it is found that the main reason of nozzle failure is nozzle drop and inner diameter enlarging caused by high flowrate and high pressure in the first jetting, as well as back pressure impact caused by the jetting fluid. The nozzle needs to be changed for the second jetting. By using law of energy conservation and data of surface jetting simulation, it is calculated that the needed jetting speed for the blockage between casing and formation, speed loss at the nozzle, speed loss to resist hydrostatic column pressure, and speed loss caused by flow back fluid, and the surface critical discharge rate and corresponding depth are obtained. When performing the jetting and fracturing tests on 3 horizontal wells with 21 sections, the discharge rate for the first section is higher than the critical discharge rate, and the following sections are using nozzle protective method. The success on 19 sections proved the method a reliable way to increasing the nozzle lifetime. In 2012, hydraulic jetting fracturing was performed with small proppant volume in reservoirs like bottom water driven reservoir in ChangQing area, and 1 to 2 times of fracturing BHA changing were decreased, which increased the production efficiency and decreased the operation cost.