Early detection device of gas cut in oil and gas drilling based on measurement of impedance

Abstract

The invention belongs to the technical field of gas cut monitoring, and relates to an early detection device of gas cut in oil and gas drilling based on measurement of impedance. The main structure of the device comprises hollow pipes, through holes, prisms, chamfers, grooves, measuring circuit boards, lead wires, poles, cover boards, pole fasteners, insulated sealing layers, routing holes and bolts. By the impedance measurement and imaging method, gas cut is distinguished based on the great difference in impedance between drilling fluid and gas, the gas contents in different positions on the circumferential direction of a well casing are obtained by a plurality of poles uniformly distributed in the circumferential direction, and the early detection device is suitable for the condition that gas is unevenly distributed in the circumferential direction and improves the reliability of measurement. The early detection device has the beneficial effects of simple structure, scientific and reasonable measurement theory, convenient operation, good practicability, service environment friendliness, strong universality, low monitoring cost, strong applicability and easy popularization and use, can detect gas cut more accurately and reliably in time, and can realize early monitoring and detection of gas cut by MWD (Measure While Drilling) equipment.

Description

Technical field: [0001] The invention belongs to the technical field of gas intrusion monitoring, and relates to an early detection device for oil and gas drilling gas intrusion based on electrical impedance measurement, which can monitor the occurrence of downhole gas intrusion in real time during the oil and natural gas drilling process to realize 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 hol...

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 201610762964.9 A gas intrusion monitoring device based on annular pressure difference measurement while drilling includes a gas intrusion monitoring while drilling sub-section, a central processor and a computer terminal. Both ends of the sensor are connected with the gas intrusion monitoring device and the computer terminal, and the computer terminal sends a measurement signal to the central processor through the data connection bus, and the measurement signal is transmitted to the gas intrusion monitoring while drilling sub-section through the armored cable, and the sensor group immediately performs measurement work , get the pressure P, temperature T and depth H of the corresponding position, calculate the actual drilling fluid density, if the difference between the actual drilling fluid density and the theoretical density is greater than the gas invasion discrimination value, start the well control preventive measures; Chinese patent 201510046076.2 discloses a The gas invasion early monitoring device during the drilling process includes a downhole monitoring device and an uphole monitoring device. The downhole monitoring device measures the sound wave attenuation data, temperature data and pressure data of the wellbore annular fluid in real time and converts them into modulus, and then sends them to the uphole monitoring device. , the monitoring data is analyzed and processed by the uphole monitoring device, and the early warning and alarm are carried out. The downhole monitoring device includes a downhole measurement nipple, a rectangular tube, an ultrasonic measurement module, a temperature measurement module, a pressure measurement module, a power supply lithium battery, and a data acquisition and processing module. The data upload module and the mud pulse generator, and the uphole monitoring device include a mud pulse decoder, an uphole data analysis and alarm system, and the mud pulse decoder is connected with the uphole data analysis and alarm system through a data transmission line; a certain drilling method disclosed in Chinese patent 201410370774.3 In-process gas invasion type equipment includes an outlet flow detection device for detecting the drilling fluid flow at the wellbore exit, an inlet flow detection device for detecting the drilling fluid flow at the wellbore entrance, and a controller for drilling at the wellbore exit The liquid flow becomes larger, that is, in the case of gas invasion, control to increase the back pressure to the wellbore, and determine the drilling fluid flow at the wellbore outlet and the drilling fluid flow at the wellbore inlet after increasing the backpressure for a period of time. The type of gas invasion; Chinese patent 201310216987.6 discloses a kind of experimental device for simulating gas well annulus pressure and gas invasion process including air compressor (1), gas flow meter (2), rubber hose (3), fixed plate ( 4), valve one (5), lower sealing cover (6), lower air inlet cylinder (7), core holding cylinder (8), rubber sleeve (9), upper pressure measuring cylinder (10), scale (11), Pressure gauge (12), valve 2 (13), upper sealing cover (14) and central column (15); its core structure lies in the central cylinder, including: core holding cylinder (8), rubber sleeve (9), upper sealing Cover (14), lower sealing cover (6), central column (15), upper end pressure measuring cylinder (10) and lower end air inlet cylinder (7), the air compressor (1) is connected to the lower end inlet through rubber hose (3). The branch pipe of the gas cylinder (7), and the gas flow meter (2) and valve one (5) are installed along the way, the rubber hose (3) is fixed in the groove of the fixed plate (4) with a certain height, and the fixed plate ( 4) The height is equal to the height of the branch pipe of the upper pressure measuring cylinder (10), the lower air inlet cylinder (7) is connected with the core holding cylinder (8), and the lower air inlet cylinder (7) is sealed by the lower sealing cover (6), The lower sealing cover (6) and the central column (15) are an integral structure, and a rubber sleeve (9) is placed in the core holding cylinder (8), and the other end of the rock core holding cylinder (8) and the upper end pressure measuring cylinder (10 ), and the upper end pressure measuring cylinder (10) has a symmetrical branch pipe, a valve two (13) is installed on one pipe, and a pressure gauge (12) is installed on the other branch pipe, and the upper end pressure measuring cylinder (10) passes through the upper sealing cover (14) seal, and a ruler (11) is attached on the vertical direction outside the central cylinder, which is used to measure the height of the liquid level; these equipment or devices can only be found when the gas invasion is serious, so they can not realize the true meaning early detection

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