Study On Mechanism And Parameter Optimization For Perforation Of Hydraulic Sand Blast

Hydraulic sand blast slotting completion technique is a new one developed since1980's for eliminating near wellbore formation damage and enhancing permeability oflow permeability formation. It is characterized by deep penetration, no secondarydamage, large oil drainage area and marvelous operation effects, etc. Completion withcurrently general high pressure jet charges offers deepest penetration depth of 0.8m,generally 0.4m, which could not penetrate near wellbore damaged formation. What'sthe worst, because shot perforation utilizes armour-piercing principle of shot to breakand squeeze the formation to form a shot hole and create a tight rock powdersqueezed zone around it simultaneously, causing the serious secondary damage to theformation, reducing the permeability by 70-80% and the well production. This is thereason why no oil produced after perforation completion although good oil and gasshow is reported in certain well exploration data and drilling process.Hydraulic sand blast slotting completion technique is a new completion methodthat based on the hydraulic momentum law and hydraulic impulse law. Its processincludes two different erosion courses: flexible materials ablation to casing andbrittleness materials erosion to rock. After consulting a great deal of literaturematerials domestic and abroad, the author lubrates Hydraulic sand blast slottingcompletion technique principle and main effective parameters in this article.Parameters analysis for flexible materials are concentrated on five erosion parameters:impact angle, impact speed, nature of the target, granularity of the grind material,rigidity of the grind particle. Parameters analysis for brittleness materials are mainlyconcentrated on four aspects: flow parameter, work parameter, grind materialcharacter and the rock nature. Based on the theory, the experiment aim was confirmed.And experiment facilities including jet flow box, confining tank and pressurized tankwere designed and prepared. Many experiment data were collected after the over 100days' experiment. Pressure effect discharge capacity effect, grind material effect,grind material's concentration effect, granularity' effect, confining pressure's effectand rock character's effect to the experiment were concluded and the seven aspects'influence rule to the hydraulic sand blast slotting capacity was found. The calculatetemplate obtained according to the experiment data was designed for the convince tothe application on site. And the test on production site validates the viable of theexperiment research and the design that hydraulic sand blast slotting completion canget deeper shoot depth, release the contamination from the drilling completion andincrease well production.