华北地区第三系地层,是一套巨厚的泥岩页岩与砂岩沉积层,储集层的埋深一般1500-4000米,岩性胶结自下而上逐渐变为疏松,特别是上第三系地层更为松软。以往的钻井过程中,井径变化大,既有缩径段,又有“大肚子”由于泥浆性能不佳等因素,造成井壁坍塌,加之油层的分布犬牙交错,产层多厚度簿,变化大,裸眼坐封的井段受到限制,增加了测试的难度和风险性。 The Tertiary strata in North China are a set of thick mudstone shale and sandstone deposits with a depth of 1500-4000 m. The lithology cement gradually becomes loose from bottom to top, especially on the third Department of the formation is more soft. In the past drilling process, the well diameter changed greatly, both the reduced diameter section, but also “big belly” due to poor performance of the mud and other factors, resulting in the collapse of the borehole wall, combined with the distribution of layers of intertwined, the production of multiple thickness books, changes Large, open-hole wells sitting section is limited, increasing the difficulty and risk testing.