Stratigraphic Lithology Interpretation And PDC Bit Selection Method

As the PDC bit is more and more widely used, a large number of bit types appears. How to choose the PDC bit adapt to drilling formation becomes much meaningful. Contrapose the field drilling requirements, this paper puts forward a PDC bit selection mathematical model aiming at a high drilling speed and low drilling cost based on the well logging datas. This study includes three parts, the first is to establish lithology interpretation model according to the adjacent well logging data;The second part is about the PDC bit wear prediction; then quantify the PDC bit structure features and establishes a PDC bit selection method based on the rock mechanics parameters uniaxial compressive strength(UCS) and rock drillability(Kd).Combining the practical situation of the oil drilling, the paper proposes multiple well lithology interpretation model based on the modle now we have. This method can draw multiple well rock mechanics space curve and predict lithology of the undrilling wells. The results is more in line with the reality and also provides a accurate basis for PDC bit selction.The research contains two main aspects about PDC bit selection mathematical model. One is the quantitative characteristics of PDC bit structure, the other is to recommend the characteristics of PDC bit. The blade number, diameter of the tooth, tooth density and the crown shape are quantified on the basis of the IADC codes. According to expert experience, the paper sets coefficients for different rock mechanics parameters and calculate the length of the different different rock strength, then the formula of the PDC bit selection for whole well was put forword.The author plans for the system based on the above model and methods and develops the system to assist with the PDC bit selection. Selection result is consistent with the practical application, which indicates that the validity of the PDC bit selection model.