Research Of Technology On Resistivity Logging In Cased-well And Its Applications On Development Inspection Of The Reservoir

Cased-well Formation Resistivity logging is one of the new well- logging methods which was proposed during the later 90's, because of its capability of measuring the formation resistivity in cased borehole, which is very different from the traditional open-hole well logging, it can be used in different stage in oil and gas development. In recent years, because of many oil fields around world into middle and final development stage, this technology has attracted on much more attention on applications to mature oil fields in petroleum industry. However, the complexity of affecting factor and the weak signal in Cased-hole Formation Resistivity logging, prevent us from accurately simulating the log responses of the subsurface complex formation. To the limit of my knowledge, there is not any data processing and explanation system that is able to handle Cased-hole Resistivity logging field data comprehensively.Simulation methods for Cased-hole resistivity had been existed, is too simple to simulate the real well-logging environment to meet the actual situation of logging, not to inspect the impact, such as cement and other factors etc on measurement instruments. Methods of measurement correction Existing for cased-hole resistivity can only rely on the chart to read and corrected manually. Instrument design parameters in the theoretical analysis, from the open literature, are only sporadic, qualitative discussion, and understanding for key parameters on instrument design, such as the operating frequency instruments, apparatus measuring the magnitude signal, electrodes space, electrodes to detect characteristics of tools were not done in essence.In light of the above problems, the systems in paper have been formed, which can simulate the conditions of the complex borehole in casing, can be used for equipment parameter inspection and theoretical analysis of the impact of factors. Cased-hole formation resistivity simulation system include, improved transmission line theory and solving surface equation of the boundary element theory. With the boundary element theory, logging response can be derived at the same time the existence of the casing, cement, etc. Use of the simulation results by boundary element theory, magnitudes relationship between electrodes space and measurement signals, and the relationship between electrodes and vertical resolutions have been analyzed, Also based on the design requirements of instrument, focusing operation frequency, the impact of casing fluid shunt for measuring, and the instrument to detect characteristics of the electrodes have been inspected. Based on the magnitude of the measurement signals from simulation analysis, and the weak signal detection characteristics from the theory, the design of the apparatus of weak signal detection circuit and high-power transmitter were analyzed, which have founded from the theoretical aspects to tools development. Correction system for resistivity logging in cased hole has been established in paper, including on condition of non-uniformity casing, formation having shoulder, cement layer. Non-uniformity correction formula in Casing is based on the principle of electrode interchangeability was derived which thereby reduce the impact of its measurement. And formulation for impact correct of the cement layer and shoulder formation, which were used in software, is calculated from the calibration chart in paper. 13 well data cased-hole resistivity logging in the eastern and west oilfield in China having been processed, results show correction formulation by software automatable had better results.Data processing and interpretation methods have been established for the cased-hole logging, based on the characteristics of different geological regions, providing interpretation results for cased-hole resistivity data. Combined with data in open hole and cased-hole, it can analyze clay content reservoir, irreducible water saturation, and then receive the original oil saturation, residual oil saturation. And then with the calculated or tested the reservoir permeability, water content and the efficiency of production, primarily on the basis of changes in oil saturation, the reservoir's water flooding is divided into four flood-level standards from the change in residual oil saturation. Field testing data suggests that the cased-hole formation resistivity log data is capable of accurately evaluating of complex reservoir and dynamically monitoring the development process. Before the application of cased-hole resistivity logging information, because of not distinctly understanding flooding layer and distribution of residual oil, the effect of oil layer treatment got worse, and with increased water content, workload water of shutoff gradually increased, the efficiency of water injection decreased, oil output measures had been showed a clear downward trend. Calculated the residual oil saturation by interpreter system can be drawn in different periods of the vertical and planar residual oil distribution in reservoir, and had been launched to evaluate the remaining oil layer to open the potential for the development of the adjustment program for the reservoir to adjust the implementation of infill drilling wells to provide deployment, also provided a strong help for reservoir description and reservoir management. Furthermore, it will be one of the intuitive and effective methods of reservoir dynamic description and management.