氯化钙无土相钻井液体系在苏丹水平井中的应用

Application of calcium chloride clay-free drilling fluids system to horizontal wells in Sudan

苏丹6区FN区块地质情况复杂,已经完钻的2口水平井在生产过程中事故频发,不但延长了钻井周期,加大了生产成本的投入,同时也对油气层也造成一定程度的损害。由此,提出了氯化钙无土相钻井液体系。此体系在FN-H3、FN-H4井上的运用,体现其具有安全、高效且环保的特点。室内研究评价和现场应用证实,氯化钙无土相钻井液体系具有良好的抑制性,能够有效地防止井壁垮塌。这种体系还具有极好的携带性,使钻井液获得较好的动塑比,充分解决了水平井施工中岩屑上返不畅的问题。另外,这种体系钻井液的加重剂不使用重晶石而改用氯化钙,从而加强了对油气层的保护,可大面积推广应用。

Since the geological conditions are complicated in FN block of Block VI in Sudan, so accidents occur frequently in the production of the two horizontal wells that have been completed. As a result, the drilling cycle is prolonged, the production cost is increased, and certain damage to oil and gas zones is caused, To overcome the problem, the calcium chloride clay-free drilling fluids system is developed. It has been applied to the FN-H3 and FN-H4 wells. Application results show that the drilling fluids system features in security, high efficiency, and environmental protection. Laboratory evaluation and field application show that the system has strong inhibition and can effectively prevent well collapse. What＇s more, it has excellent carrying capabilities, which will enable the drilling fluids to obtain high dynamic plastic ratio. This can solve the problem of unsmooth returning of cuttings completely. In addition, calcium chloride is used as the weighting agent of the drilling fluids instead of heavy spar, which strengthens the protection of oil and gas zones and can be widely applied.