Study on the Method of Obtaining Formation Rock Mechanical Parameters by Group Cuttings Method

Abstract

In drilling engineering, the mechanical properties of formation rocks are essential basic geological parameters. One of the most important tasks at the drilling site is to grasp the mechanical properties of the formation rocks timely and accurately. We take the readily available cuttings on site as the research object to test the compression characteristics. The experiment shows that the compressive stress of group cuttings with the uniaxial compressive strength of rock has an obvious correlation. The relationship model between compressive stress of cuttings compressed to 105% of original rock density and uniaxial compressive strength of original rock is established, and the results conform to an exponential function. When cuttings with different particle sizes (2-10 mm) are used, the coefficient values before the exponential term of the model are stable and the same, only the coefficient of the model is slightly different. The Group cuttings method can reduce or eliminate the disadvantages of discrete experimental results caused by a single cutting defect and individual differences. The new method takes cuttings returned from the drilling site as the test object, which is convenient and quick and can provide a way for the site to obtain the rock mechanics parameters of the drilled formation timely and accurately. Introduction Rock mechanics plays a significant role in the petroleum industry, especially in oil & gas drilling and development projects. The study of rock mechanics aims to know the geological engineering parameters such as rock mechanics properties of the reservoir, understand and master the change law of rock mechanics properties, and apply this law to drilling engineering (Qin, 2014). The work includes formation rock drillability analysis, reasonable bit selection, drilling parameter optimization, and wellbore stability analysis. It is one of the most critical tasks to grasp the mechanical properties of formation rocks in time and accurately (Lin, 2014).