Energy Reports (Nov 2020)
Optimization and application study on targeted formation ROP enhancement with impact drilling modes based on clustering characteristics of logging
Abstract
Rate of penetration (ROP) is affected by many factors (i.e. rock properties, drilling parameters), and the increase of ROP is required to meet the needs of modern drilling operations. This paper presents a methodology to increase ROP by developing targeted impact drilling plans according to classify rock mechanic parameters of the different formations. In this paper, rock mechanic parameters are calculated based on well logging data, and the results are clustered according to unsupervised clustering algorithm. Then, the clustering data are used as the material parameters for numerical simulation, and the rock-breaking performance of polycrystalline diamond compact (PDC) cutter in different formations under determined impact load and, cutting velocity is discussed as well as the coupling of these two factors. It is shown that the crushing volume of the rock clustering from upper softer formations can be significantly increased by coupling impact load and higher cutting velocity while maintaining the lower specific energy consumption. In the cluster rock of harder formations which needs maximum mechanical energy to break, impact load can greatly reduce its specific energy consumption. However, after increasing the cutting velocity, the specific energy increases greatly while the rock crushing volume increases insignificantly, which is not expected in the drilling. According to simulation results, the paper developed two ROP enhancement modes, using impact drilling mode (Drilling Pipe+ Axial Impact Hammer+ Bit) in well interval of harder volcanic rock formations drilling while high-speed rotary impact mode (Drilling Pipe+ Positive Displacement Motor+ Axial Impact Hammer+ Bit) drills the well interval of upper softer formations. The feasibility of these modes has been verified by field experiments. The figures show that compared with offset well which drilled by positive displacement motor (PDM), high-speed rotary impact drilling increases ROP by 48.44% on average in three trips in the well interval of upper softer formations. Meanwhile, conventional impact drilling mode has the strongest ROP improving ability in the well interval of harder volcanic rock formations, reaching 113.45% in the fourth trip, and also has the advantage of saving PDM rental costs.
