Casing program optimization and application of ultradeep wells in Shunbei oil and gas field

As the exploration and development of Shunbei Oil and Gas Field advances continuously, the burial depth of oil reservoirs increases continuously and the limitation of original casing program emerges gradually and impacts the drilling speed and safety. To solve this problem, the casing program design method of " from the top to the bottom” or " from the bottom to the top” was adopted according to the stratigraphic characteristics. The casing depth and size were determined based on the formation pressure distribution and the setting position. In the simpler areas, the four-stage casing program was simplified into the three-stage casing program of Ø193.7 mm casing. In the areas with intrusive bodies, the six-stage casing program was optimized into the four-stage casing program and the Ø120.6 mm hole was optimized into the Ø143.9 mm hole to satisfy the demands of directional drilling. In the Paleozoic saline aquifers, high-pressure gas layers and the areas with complex pressure system, the unconventional casing (Ø184.2 mm, Ø206.4 mm and Ø219.1 mm) was adopted and the setting position was optimized, so that the casing program suitable for complex strata was developed. By simplifying the casing program and optimizing the casing program in complex areas, the rate of penetration and the drilling efficiency are improved and the safe drilling is ensured.