Analysis Of Rock Mechanics Characteristics And Drill Selection In Megaidi Region

Improving the footage and reducing drilling cycle is the most effective and most direct means to reduce drilling cost. Improving bit performance by reasonable and scientific bit selection method is the measures to realize high effective and safe drilling.Through the investigation of the evaluation of rock mechanics properties and current bit selection method, this paper selected compressive strength, shear strength, drillability, hardness, abrasive resistance and formation drillability as parameters to evaluate the mechanical properties of rock. These parameters have great relevance with the logging data, and logging data has the characteristics of continuity, high-accuracy, accessibility and economic practicability, so using the correlation between the logging data and the rock mechanics parameter, we can establish continuous profile of rock mechanics parameters varying with depth. According to the variation trend and distribution of rock mechanical parameters, we can analysis the section profile using cluster method. According to the principle and method of clustering analysis, we can mark off the formation into small layers with same performance, and selected suitable types of bits according to the mechanical properties of each layer.Based on the geological conditions of Mengaiti area, this paper analyzed the rock composition and its content of the rock, and established the lithologic section. Using the relationship between the rock mechanics parameters and logging data, this paper draw the profile section of rock mechanics parameters, and analysis of rock mechanics characteristics. This paper established the theory model to divide layer with rock mechanics parameter according to extreme value of hierarchical clustering method, which provide basis for bit-selection.Starting from the rock mechanics characteristics, logging curve of nine representative wells were interpreted, and extracted the mechanical parameters of rock strata, hydraulic and mechanical parameters corresponding from different types of bits, established a sample database of bits.With a large amount of research, this paper formed bit selection process for wells to be drilling in the Mengaiti area. First, deal with logging data of the drilled adjacent well, and establish the profile of rock mechanics parameters varying with depth. And then using the gray correlation analysis method, according to the mechanical parameters of rock strata, carry out bit-selection for each hierarchical layer of wells to be drilled, select several bits which have high correlation with rock for each hierarchical layer. Finally, refer to lithology and mechanical parameters of each layer, delete unsuitable bits of the formation and recommend optimal bits.Based on the above method and process, this paper established a set of application software for the stratigraphic division and bit-selection. and carry out applications on two wells to be drilled through this software. The bit-selection test results show that, compared with similar wells, the average single bit footage is increased by24%, the average ROP is increased by26.11%, average ROP of third spudding is increased by33.58%, the average drilling period is shortened by11.97%, this method and process greatly improve the drilling speed, shorten the drilling cycle, achieve good results, which can provide help for bit selection in Mengaiti area.