Study on the law of drillability of stratum in ShunBei #1 block

Abstract

ShunBei 1 block is located in the northwest of Shuntuoguole low uplift in the north of Tarim Basin, with a block area of 4453km2. The reservoirs are mainly distributed in the Middle Ordovician carbonate rocks, and the burial depth is generally more than 7500m. A large number of strike-slip fault zones are developed in ShunBei #1 block, which results in low drilling rate, difficult drilling and poor formation drillability. In this paper, through rock drillability experiment and acoustic test experiment, the experimental analysis of the core of the study block is carried out, and the fitting relation formula of drillability level value is determined by comparing a variety of fitting methods. Based on the calculation model of drillability class value, this paper calculates the drillability class value of Well X in No. V fault zone of ShunBei #1 block, and establishes the drillability profile of Well X. Through the analysis of the drillability profile and drilling conditions, it is believed that with the increase of formation depth, the drillability class value of formation increases, and the drillability of formation becomes worse. Because the fluctuation of the strata drillability class value in the fault zone is small, but the strata drillability class value is large. The drillability class value of induced fracture zone strata changes dramatically, showing obvious sawtooth shape, but in general, the value of drillability class value is consistent with that of conventional strata. The strata drillability level of sliding crushing zone increases obviously, but its fluctuation is small. In addition, the drillability of the strata under different fault types is compared. It is concluded that the drillability class value of the strata controlled by the compression fault zone and the strata controlled by the translation and pull-apart fault zone fluctuates very little, but the drillability class value of the strata controlled by the compression fault zone is larger, and the formation drilling difficulty is greater, and the drillability is worse.