Research On The Formation Drillability Of Longshen 3 Block

Rock drillability is the main indicator in the process of drilling for the drilling methods choice, bit type selection, and drilling speed determination. It is also a necessary basic data in drilling engineering, which has important application value for drilling engineering operations. Therefore, the representation and determination method of the rock drillability is an essential work in drilling engineering. In recent years, Longshen 3 block has become one of the key developing blocks in Jilin oilfield. Its efficient development is a significant assurance to fulfill the goal of high-efficiency production capacity construction. Longshen 3 block is buried about 3400 m deep and belongs to the tight gas reservoir with low pressure. At present, there exist a series of problems, such as the low drilling speed, less footage of single drill bit and poor borehole stability, which bring some great difficulties and challenges for drilling operations. In order to improve drilling efficiency, shorten drilling time and ensure the safety drilling, the prediction research on the drillability and abrasiveness of Longshen 3 block has been carried out in this paper and the correlation model is established.Based on the logging information and core data of Longshen 3 block, the experimental study on the hardness, plasticity coefficient, abrasiveness, drillability of the rock in Longshen 3 block has been carried out at the normal temperatures and pressures and the related theoretical analysis is conducted. The relationship of the drillability, abrasiveness and rock mechanics parameters is concluded. Through the drilling rate equation and wear equation of PDC bits, the rock drillability and abrasive coefficients are calculated and they are corrected by the experimental measured data regression. Using the mathematical statistics method to establish the relevance model of the drlling resistance parameters and logging parameters, the dependent equation of the drillability and interval transit time in Longshen 3 block is obtained. The relationship between the drillability grade value under the confining pressure of Longshen 3 block and uniaxial drillability grade value is analyzed. Finally, the drilling resistance characteristics profile of single well under different drilling fluid density is predicted and the bit design of Longshen 3 block is improved.