Research On Optimization Design Of Multistage Fractures In Hydraulic Jet Fracturing Of Horizontal Well

In oil-gas exploitation process, horizontal wells have a series of advantages comparedwith the conventional vertical wells, such as large drainage area, high production in singleborehole, high reserves producing degree, and so on. However, the production still is low inmost horizontal wells for low permeability reservoir, and it can meet the demand foreconomic development. So, in order to raise the production in single borehole and theultimate recovery and improve the economic benefit of oil exploitation, reservoir stimulationneeds to be conducted in horizontal wells. Especially in recent years, with the breakthroughof the staged fracturing technology in horizontal wells, the production in single well is raisedsubstantially and the further development of low permeability oilfield in China is promotedgreatly. But the current theory is obviously insufficient aiming at the staged fracturingtechnology in horizontal wells. Especially the study on the productivity calculation andparameters optimization of fractured horizontal wells and is not perfect, and it is urgent todevelop deeply the theoretical study to meet the needs of practice.First, this paper has built two productivity calculation models respectively based onSVM and theory function.Second, fracture parameters which are optimized according to theproductivity calculation models built by theoretical derivation, the parameters have greateffects on the productivity of fractured horizontal wells. And the results shows that when thefracture half-length is150~170m, the number of fractures is10~12, the fracture conductivityis300md·m, and the fracture interval is about80m, the best possible optimization is achievedfor ultra-low permeability reservoirs with the permeability of0.1-0.5md. Last, the softwareE-stimuplan is used to optimize the construction parameters aiming at the optimized fractureparameters. And it comes to that when the amount of fracturing fluid is150~175m3, theamount of adding sand is30~35m3, the displacement is3m3/min, and the percent of pre-padfluid is30%, the best possible optimization of construction parameters is achieved.