The Chuandong Northern Feixianguan Group Exploratory Well Formation Pressure Logging Forecasting Methods And Engineering Applications

Well logging technology has been playing an important role in petroleum drilling engineering Because of the continuity, economical efficiency, reliability and high resolution, well logging has shown its great advantages, especially in some drilling engineering problems, such as prediction of rock drillability & selecting the bit types, predicting formation pressure, calculating the In-situ stress, evaluating the borehole walls stability and determining the reasonable mud density, etc. Aiming at the engineering accidents, for example the well spout, well leak, well collapse and the drill blocking during the drill engineering in the T formation in North-east of Sichuan, taking the FeiXianGuan formation of Well Lj9, Du4 and Zi2 and etc as studying object, some farther studies of T1x formation pressure and its drilling engineering application by using of well-logging information are especially presented in this dissertation.The recognition of Lithology and reservoir type is the geological foundation to explain the formation pressure by using logging data. Firstly, this study uses the complex lithology analysis approach to interpret the lithology and physical property of carbonate profile. Secondly, on the basis of general discrimination of carbonate reservoir types, fractal-dimension technique is adopted to calculate the fractal characteristics of logging curves (Df), and to deduce new arithmetic of porosity index (m) and their connection to reservoir type. And thus the carbonate reservoir type is discriminated effectively.The formation pressure system includes the overburden pressure (Po), formation pore pressure (Pp), fracture pressure (FP) and breakout pressure (BP). Focusing on the problem that to estimate formation pore pressure is relatively difficult, the effectiveness stress method is used to predict the formation pore pressure of the carbonate. Result shows that the method has higher accuracy for calculating formation pore pressure of the carbonate formation.Using logging information can decide the size and direction of In-situ stress, and then determine stratum fracture pressure and breakout pressure so can provide the suitable mud density to solve the mechanics instability of borehole. This thesis integrates the borehole collapse model with the artificial fracture and imaging well logging to get the size and direction of In-situ stress, and set up the reasonable prediction model of stratum fracture pressure and breakout pressure for carbonate profile, by making use of the rock mechanics parameters from logging information, based on comparing the present various prediction models. Based on three-constructed formation pressure of the carbonate logging calculation models, the securewindow of mud density is given to guard against well collapse for the carbonate formation of research region.The common types of the carbonate borehole wall losing stabilization are briefly presented. The collapse mechanisms and reasons are researched according to types. Based on a variety of elements aroused the borehole losing stabilization in the actual drilling process, the countermeasures are proposed to guard against these complex accidents. Meanwhile, the predicting method of stress is proposed based on BP's neural network by using the seismic interval velocity, in order to predict borehole wall stability. The process result declares that the mud density scope is from 1.05 to 1.5g/cm3 to keep the exploratory well borehole wall stabilization of carbonate formation in SiChuan east-north oilfield.Rock drillability test is the foundation to predict rock drillability from well logging data. This essay adopts the neural network and regression analysis technique to set up the some logging parameters prediction model of the rock drillability, and deduces creatively the theoretic relation of the formation pore pressure(Pp) and the rock drillability(Kd). Further, verify this theoretic relation between Pp and Kd from core drillability data of Du4 well and the result of formation pressure. All the study show that this method is feasible and...