| The domestic and foreign researches show that the tight sandstone gas reservoirs mainly have the following characteristics: ① low porosity and permeability, small throat passage pore, fractured formation; ② strongly hydrophilic sandstone, larger surface area, high irreducible water saturation; ③ strongly heterogeneity of reservoir rock, potentially trapping water damage induced by water intrusion. Development methods are mainly small hole technology, horizontal technology and underbalanced technology. The stimulation technologies include hierarchical fracturing and horizontal transformation technology.Combining he practical application of drilling fluids with indoor drilling research of the conventional horizontal well and horizontal high temperature, the basic recipe of conventional horizontal well is determined: water+0.3% caustic soda+0.8%viscosifier ZFV-H+fluid loss additive SW-FL+5% bituminous block agent+5% micronanometer diversion agent WNF+4% KCl+5%diesel oil+KCl or organic salts. the basic recipe of horizontal high-temperature well is water+0.3% caustic soda+0.8%viscosifier ZFV-H+3% sulfonated lignite+3% sulfonated phenol formaldehyde resin+5% bituminous block agent+5% micronanometer diversion agent WNF+ 4% KCl+5%diesel oil+organic salts.According to water sensitivity and water capture characteristic of tight sandstone gas reservoir, low damage completion fluids system are proposed. By adding the clay stabilizers, the swelling and dispersion migration of clay minerals are prohibited to avoid water sensitivity damage. By adding waterproof capture agent, gas and fluid interface tension is decreased. The low damage completion fluid is determined: water+ 2% clay inhibitor FG88+ 2% waterproof capture agent.With related evaluation methods, the preferable drilling and completion fluids are analyzed by fluid identity, permeability damage. The evaluation supports the safe and efficient development of tight sandstone gas reservoir. |
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