Drilling Design and Optimization Technology for Ultra Deep Wells in Tarim Oilfield: A Case Study of Well Take-1, the Deepest Well in Asia

The Tarim Basin is a Precambrian superimposed composite basin. The main source rocks are characterized by ultra-deep and ancient characteristics. In 2023, based on the dual goals of oil and gas discovery and scientific exploration, Tarim Oilfield proposed the deepest exploration target in China named Take-1, to explore deeper carbonate oil and gas reservoirs under the Fuman Oilfield, with a designed vertical depth of 11,100 meters. In order to achieve drilling goals safely and efficiently, pioneering work has been done in drilling design. The drilling design is based on comprehensive geological engineering research. The design of the upper casing reaches the deepest depth in the area, and engineering technical measures are adopted to achieve the drilling of multiple sets of strata. The force of wellhead tools on ultra-long and overweight casing is simulated and calculated to avoid the casing entering the plastic deformation state during the running process. Hydraulic parameters and vibration effects shall be fully considered during the design of drilling tool assembly to realize safe drilling. The research and field implementation progress show that the key technology of the drilling design of Take-1 can solve the series of drilling difficulties faced and achieve the goal of the 10,000-meter drilling project. 1. INTRODUCTION In 2023, the Tarim Oilfield proposed the deepest exploration target in China, with the well number Take-1. One of the purposes is to explore the deeper carbonate reservoirs under the Fuman oil field. The design vertical depth is 11,100 meters, and drilling commenced on May 30, 2023, reaching a depth of 10,000 meters by March 4, 2024. At present, there is only one well with a vertical depth of over 10,000 meters drilled on land worldwide, which is the SG-3 well drilled by the former Soviet Union in 1989. The completed drilling depth is 12,262 meters (Claesson et al. (2000)). The well was drilled in four sections with a 36-inch pilot hole and an 8 1/2-inch borehole, and took 23 years to complete. The Tiber well, which was completed at a depth of over 10,000 meters in the deepwater basin of the Gulf of Mexico, USA, was drilled to a depth of 10,685 meters (1,259 meters of water depth) using a seven-opening structure (Naranjo, J. C. et al. (2011)). In October 2022, Abu Dhabi National Oil Company of the UAE set a new record for the world's deepest well in the UZ-688 well on the artificial island of the Upper Zakum field, which was completed at a depth of 15,240 meters in a horizontal well (El Sabeh, K.et al.(2023)).