Abstract: Tight sandstone gas reservoirs is characterized by tightly rocks and low natural productivity. Infinite staged fracturing technology for horizontal wells is the necessary means of high efficient development for this gas reservoirs. It is difficult to implement measures such as reservoir evaluation and wellbore maintenance due to the limited segmented stages of ball throwing sliding sleeve and pipe string shrinkage, although the plug and perfortion can achieve infinite stages, but the construction is not continuous, operating costs are high. Meanwhile, those fracturing tools have single function, which cannot meet the needs of water control of production wells. According to the function requirement of "non-limited, full-bore, switchable, combined operation" gas reservoir, the theory of full-bore non-limited design is innovated, the open assembly with compound shrapnel-multi-function ball cage structure and the sliding sleeve body with position selection slot and inner rubber cylinder are designed, and the full-diameter sliding sleeve structure with infinite stage is formed. The tool system has been used to nearly 200 wells in tight sandstone gas reservoirs in Western Sichuan Basin. Compared with the same technology at home and abroad, the operating efficiency can be improved by 50%, the selective switch operation is successfully carried out in production wells such as DS103-2. It provides a new tool system for efficient development of tight sandstone gas reservoirs.

Key words: sliding sleeve, unconstrained stages, switchable, evaluation test, field test