Through casing resistivity simulation measuring method
A measurement method and technology of resistivity, which is applied in the field of analog measurement of through-casing resistivity based on the Hall effect, can solve problems such as low measurement electrodes, influence on measurement accuracy, and small second-order potential difference, and achieve simple principles and high current The effect of good signal and high measurement accuracy
Inactive Publication Date: 2016-01-27
SOUTHWEST PETROLEUM UNIV
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Problems solved by technology
When the resistivity of the formation is very low, the potential of the measuring electrode is very low, and the measurement accuracy of the instrument is limited. When the resistivity of the formation is high, although the potential of the measuring electrode is large and easy to measure, the current leaking into the formation will be smaller , the second-order potential difference becomes significantly smaller, and the measurement accuracy will also be affected
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[0018] Below in conjunction with embodiment the present invention is further described in detail.
[0019] A method for simulating measurement of resistivity through casing, comprising the following steps:
[0020] (1) Prepare the analog measuring device: such as figure 1 As shown, an annular strong magnet 2 iron is set in the casing 1 cemented with cement 4, the magnet 2 will generate a magnetic field in the direction perpendicular to the current, and the casing 1 is placed in the water tank 3, by changing the water tank 3. The salinity of middle water 5 achieves the purpose of simulating the measurement of strata with different resistivities outside the casing;
[0021] (2) Measurement: First measure the voltage signal under the condition of air outside the casing, then gradually add a certain amount of NaCl in the order of salinity from low to high, and measure the voltage response signals under different salinity conditions in turn; Hall effect, when the current passes t...
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The invention discloses a through casing resistivity simulation measuring method. The method comprises the following steps: 1, preparation of a simulation measuring apparatus: arranging one annular strong magnet in a sleeve with cement cemented therein; 2, measurement: first of all, measuring voltage signals outside the sleeve under an air condition, then gradually adding a certain amount of NaCl according to a sequence of gradually increasing mineralization, and successively measuring voltage response signals under different mineralization conditions; and 3, calculation: through a loop electrode arranged on the ground, measuring Hall current and voltage values generated in the second step, and obtaining apparent resistivity of a stratum through calculation according to a formula. Compared to the prior art, the method provided by the invention has the following advantages: measurement of through casing resistivity and a Hall effect are combined, through applying a magnetic field in a direction vertical to currents in the sleeve, Hall voltages and currents generated in the stratum through the Hall effect are recorded, and then, the apparent resistivity of the stratum is calculated. The principle is simple, the current signals are quite good, and the measurement precision is quite high.
Description
technical field [0001] The invention relates to a resistivity simulation measurement method, in particular to a Hall effect-based simulation measurement method for through-casing resistivity. Background technique [0002] In the 1980s, with the appearance of low-noise amplifiers, the first logging prototype produced by PML Logging Company was successfully developed in 1988. Subsequently, a number of patents on the resistivity of through-casing appeared successively all over the world. Schlumberger has successively updated several generations of measuring instruments, which are used in the evaluation of remaining oil in old wells and dynamic monitoring of reservoir saturation in my country. [0003] Foreign commercial through-casing resistivity logging tools are all based on the research of the former Soviet expert Alpin who proposed in 1939 to use three electrodes in the metal casing to measure the differential voltage and then estimate the current leaked into the formation...
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Inventor 陈科贵黄长兵孙嘉戌
Owner SOUTHWEST PETROLEUM UNIV