Application of Seismic Guide Drilling Technology for Ultra-Deep Buried Carbonate Reservoir

Abstract

Fracture and cavity carbonate reservoir are a kind of highly heterogeneous reservoir controlled by dissolution. The reservoir space is mainly composed of caves, pores and fractures, which is characterized by moniliforme reflection in seismic. This kind of reservoir is mainly distributed in Tabei and Tazhong area of Tarim Basin in China, which is rich in oil and gas resources. However, due to the limitation of reservoir scale, the productivity of single well is relatively lower than clastic reservoir, showing the characteristics of “one cave one reservoir”. Therefore, the success rate of drilling plays a decisive role in the production and economic benefits of the reservoir, especially for the ultra-deep wells with a depth of more than 6000 m. In order to ensure the accuracy of drilling into reservoir, avoid drilling failure and improve economic benefits, this paper proposes a while drilling seismic guide method for fracture and cavity carbonate reservoir, which is based on the accurate seismic calibration while drilling, combined with formation dip angle analysis and seismic processing while drilling. It can determine the exact location of reservoir while drilling, so as to adjust the well trajectory in real time if necessary, to get the purpose of improving the drilling success rate. This method has been applied in Tazhong area of Tarim Basin, which has been used in 82 wells in the last three years, and make the success rate improved to 90.7%.