A method for early detection of gas invasion in oil and gas drilling based on electrical impedance measurement

Abstract

The invention belongs to the technical field of gas intrusion monitoring, and relates to a method for early detection of gas intrusion in oil and gas drilling based on electrical impedance measurement. The measuring nipple is connected to the drilling tool at a place close to the drill bit or downhole dynamic drilling tool, so that the electrode and the wellbore drilling fluid are connected. Then connect the measuring nipple with the downhole signal transmitting device located in the downhole, the signal transmitting device is wirelessly connected with the signal receiving device located on the ground, and finally connect the signal receiving device with the data processing computer, and apply current excitation to the electrodes, Establish an electric field in the drilling fluid, measure the potential data on other unexcited electrodes, and analyze and process the signal transmitting device, signal receiving device and data processing computer to realize the judgment of whether gas invasion occurs and the degree of occurrence of gas invasion; it can be accurate, Timely and reliable detection of gas intrusion, early monitoring and discovery of gas intrusion can be realized by using MWD equipment, which has the beneficial effects of low monitoring cost and strong applicability, and is easy to popularize and use.

Description

Technical field: [0001] The invention belongs to the technical field of gas intrusion monitoring, and relates to an early detection method of oil and gas drilling gas intrusion based on electrical impedance measurement. During the oil and natural gas drilling process, the occurrence of downhole gas intrusion can be monitored in real time to achieve the purpose of early detection. Background technique: [0002] Gas invasion is a process in which gas invades into the drilling fluid and deteriorates the performance of the drilling fluid during drilling. Gas invasion has a certain impact on the pressure of the drilling fluid column, and the density of the drilling fluid for gas invasion is different at different depths. The density of the invading drilling fluid becomes very small when it is close to the surface, so even though the surface drilling fluid gas intrudes heavily and the density drops a lot, the pressure reduction of the drilling fluid column at the bottom of the hole...

AI Technical Summary

Problems solved by technology

[0003] In the prior art, gas invasion monitoring methods are generally divided into two categories: one is to install measuring equipment on the ground or near the wellhead, and realize gas invasion monitoring by monitoring ground or near-surface parameters, including drilling fluid pool liquid level Gas breakthrough monitoring method, drilling fluid return flow meter gas breakthrough monitoring method and acoustic gas breakthrough monitoring method, etc. These methods belong to indirect judgment methods, and the time lag for gas breakthrough detection, the greater the well depth, the longer the lag time, and the gas breakthrough cannot be realized. The other type is to directly place equipment downhole, and realize the judgment of gas breakthrough by detecting downhole parameters, including the gas breakthrough monitoring method based on formation resistivity. The purpose of "early" detection of air intrusion

These methods have their own characteristics, but they have relatively large limitations in use: the method of measuring formation resistivity to determine whether gas invasion occurs is not the drilling fluid most obviously affected by gas invasion, and logging-while-drilling equipment is required. The cost is high, and the effect is affected; the characteristic parameters obtained by measuring the pressure of several points in the wellbore annulus to obtain the density change of the drilling fluid and measuring the sound wave attenuation characteristics of the entire wellbore are for a certain well section or the entire wellbore; disclosed in Chinese patent 201310010487.7 A gas invasion position detection method in the drilling process is based on the different propagation speeds of pressure waves in drilling fluids with different gas content to determine gas invasion and detect the gas invasion position. The action of the hydraulic throttle valve (4) generates pressure waves, pressure waves Propagate to the bottom of the well along the annular space (7), and return to the ground through the mud in the drill pipe (8) and the mud in the annular space (7) after reaching the bottom of the well; according to the standpipe pressure sensor (2) and the casing pressure sensor (1) The time difference of the pressure wave reflected back from the bottom of the well is received to determine whether gas kick has occurred. According to the detected wellhead gas-liquid flow rate, casing pressure, and pressure wave propagation time difference in the annular space (7) and the drill pipe (8), the annular The air-hydraulic model performs Runge-Kutta iteration on each parameter to obtain the distribution of void ratio and wave velocity response time at different positions in the annulus, and to determine the one-to-one correspondence between the air intrusion position and the pressure wave response time, thus obtaining the occurrence Accurate location of gas intrusion; Chinese patent 201510689849.9 discloses a deep water drilling gas intrusion monitoring method based on riser gas-liquid two-phase flow identification, which is to install an ultrasonic probe at the bottom of the riser to monitor the gas intrusion signal. Quantitative correspondence with cross-section gas content, combined with deepwater drilling wellbore gas-liquid two-phase flow model and formation pressure prediction method with reliability, establishes a wellbore gas invasion degree inverse calculation method based on gas invasion monitoring data at the riser, which is accurate in advance While discovering gas invasion, realize real-time quantitative description of wellbore gas invasion, thereby forming a deepwater drilling gas invasion monitoring method based on riser gas-liquid two-phase flow identification; Chinese patent 201710241483. The wave signal real-time monitoring method of gas invasion uses the pressure pulse fluctuation signal generated by MWD when transmitting downhole data as the pressure wave source, and the pressure wave signal propagates along the two paths of the annulus and the drill pipe to the surface annulus pressure sensor and the standpipe pressure sensor respectively , and then filter the pressure wave signal received by the two sensors through the filter processor, amplify the filtered weak signal through the weak signal amplifier, calculate and record the pressure pulse signal through the data processing and real-time monitoring system and return it from the two lines The time difference on the ground, and finally the alarm judges whether to carry out early warning and alarm according to the time difference; these methods can only be found when the gas intrusion is serious, so it cannot realize the real early detection

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