Chuandong Feixianguan Formation Pressure Log Interpretation Methods

With the development of petroleum exploration toward the deeper formation and the offshore, the application of logging technology in petroleum engineering has been becoming more and more important. Because of the merit of continuity, economical efficiency, reliability and high resolution, the well logging has shown its advantages, especially in some drilling engineering problem, such as the prediction of rock drillability, selecting the drill bit types, prediction of formation pressure, calculation the In-situ stress, evaluating the borehole walls stability and determining the reasonable mud density, and 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, some farther studies of formation pressure in FeiXianGuan from well-logging information are presented in this dissertation.Stratum lithology and reservoir type recognitions are the geological foundation to explain the formation pressure by using logging data. Firstly, this study uses the NewCRA complex lithology analysis technology to interpret the lithology and physical property of carbonate profile. Secondly, on the basis of general discrimination of carbonate reservoir type, adopts fractal and fractal-dimension technique to bring forward the fractal characteristics of logging curves (Df), new arithmetic of porosity index (m) and their connection to reservoir type, thus discriminates the carbonate reservoir type effectively.The formation pressure system includes the overburden pressure (P0), formation pore pressure (Pp), fracture pressure (FP) and breakout pressure (BP). The most popular method, equivalent-depth method is used to predict the formation pore pressure in sandstore profile. Research indicates that this idea is also applicable for the carbonate. To set up a suit of idea of travel time reading of carbonate interval and use real pressure data to correct it during plotting the normal compaction trend curve are rather important. The method is applied to the prediction of formation pressure in LuoJiaZhai and DuKouHe oilfield successfully.Using logging information can make the size and direction of In-situ stress, and then determine 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 fracture pressure and breakout pressure for carbonate profile, by making use of the rock mechanics parameters from logginginformation, based on comparing the present various prediction models.Rock drillability test is the foundation of prediction rock drillability from well logging data. This essay adopts the neural network and some parameters regression analysis to set up the some logging parameters prediction model of the rock drillability, then gets the continuous drillability classification value of single well formation. And deduces the theoretic relation of the formation pore pressure and the rock drillability creatively.Based on the above methodological analyses and practical situation of FeiXianGuan interval in the LuoJiaZhai and DuKouHe structure on the east of Sichuan, a set of well log interpretation formation pressure application program is developed. It has been successfully applied to the fine interpretation of LuoJia4 well and Du4 well, and so on. The results of formation pore pressure, fracture pressure and breakout pressure are all accordant with the practical situation. Moreover, the mud density has been validated in practice.