在本国花岗岩,片麻岩和其它结晶岩石中有数以千计的6英寸直径的民用水井,但在这些硬岩地层中,大直径水井较少。似乎只有在裸眼中配用6英寸水泵或者要求风动冲击钻进深眼时才钻大直径水井。在这些岩层中,水井的出水量往往不是钻大直径水井的主要理由。然而我们在新英格兰看到的钻井表明,增大水井直径对水井出水量和水井性能有良好的作用。 There are thousands of 6-inch diameter civilian wells in native granite, gneiss and other crystalline rocks, but fewer of these large-diameter wells are in these hard-rock formations. It seems that only with the naked eye with a 6-inch pump or require pneumatic impact drill deep into the eyes when drilling large diameter wells. Of these rock formations, the water outflow from the well is often not the main reason for drilling large diameter wells. However, the drilling we saw in New England shows that increasing well diameter has a good effect on well water discharge and well performance.