Wash well flushing of the injection wells are an important aspect of the injection well test Note. The purpose of flushing is repeated washing water injection layer filtration surface of the casing wall and tubing inside and outside wall adhesion of the impurities, dirt, to ensure the cleaning of injection wells, to prevent dirt injected into the reservoir officially injection. Flushing requirements on injection wells, large displacement and stability.
Injection wells to wash well, according to the different water injection obviousness. No matter the kind of flushing wash well, must be continuous, in the middle can not stop to prevent the precipitation. Generally are water injection wells, and wash well to take the washing → backwash → washing; anti Note horizontal wells wash well take backwash → are washing → backwash. Sand sand sand production is the four victims in the oil field development (sand, wax, water, thick), one of a direct impact on the implementation of technical measures of oil production and oil field development program. Therefore, we must analyze the reasons of the oil wells, sand, master sand and sand of technical measures.
A reservoir of sand cause sand production for many reasons, but can be summarized in geology and development of two reasons.
A. (1) geological reservoir osteoporosis caused by the nature of the sand reservoir out of the root causes of sand and oil-bearing sandstone. And rock particles, the nature of the cement type and content and cementation, fluid in the pores of the rock. Cement content of sand is easy to sand, and high cement content of the reservoir is relatively strong, difficult to sand. Cement of the sandstone, the general strength of the siliceous cement, carbonate cementation, followed by the worst clay cement. (2) also affect the physical properties of the fluid in the formation sand production. Such as high oil viscosity, gas content of the reservoir is easier to sand. (3) formation in the structure changed dramatically. Easy to sand in many faults, fracture development, the dipmeter Japanese edge water active regions, the local layer structure were destroyed.
Two. Oil field development (1) oil wells, sand control system is unreasonable. Wells nozzle is too large, strongly pumped drain, gas lift wells violent blowout will cause the reservoir structural damage, causing a lot of sand. (2) well water caused by sand. Water erosion reservoir cement, and the destruction of the cement between the rock particles. Argillaceous cement of the rock more easily rupture and cause the sand. (3) measures to improper sand. Frequent stimulation augmented injection measures will destroy the rock structure. Fracturing, such as reservoir rock with high-speed liquid impact, weaken the cementing force between the particles of rock and acidification also destroy the rocks cemented, dense perforation broken rock, and even lead to the destruction of the casing, which would give rise to sand. (4) improper well construction can easily lead to sand production.