| Salt drilling, in deep wells particularly, is a big challenge to the world. Due to the creep of the salt, lots of deep wells were finished before target zone or accidently finished or casing collapse, leading to great economic loss. Pre-Caspian Basin is very rich in oil and gas, but thick layer of salt widespread in the region (ranging from several hundred to several kilometers), which is a big challenge to drilling. Therefore, the priority of oil and gas exploration in the basin is how to drill through the salt safely and fast. The key to solve the drilling problem is to properly analyse the creep law of the salt, which is the necessary basis for drilling fluid density design, well stucture design and casing design. Salt sample and core were gathered from Kazakhstan Pre-Caspian Basin, and after analysing physical, chemical and creep property experimentally, the creep model for the super thick salt at Pre-Caspian basin were established, and also, the drilling fluid density design method for drilling salt in this area was presented. Drilling practice of three wells proved that the density from this method could ensure safety drilling. And so this design method provides a reliable technical support for the oil and gas exploration beneath salt at Pre-Caspian Basin. |
