| With the deepening of oil and gas resource exploitation,the oil and gas reservoir environment are becoming more and more complex and exploitation difficulty is increasing.The traditional general completion method is no longer able to meet the needs of production management and optimization for complex oil and gas wells with special structures.The research and development of intelligent well systems and related technologies have provided solutions to solving the above problems.However,the structure of the intelligent well string is much more complex than the conventional general completion string.If there is a lack of a matching intelligent well string inspection system,the effectiveness of injection and production will be directly affected.In severe cases,it will reduce the service life of oil and water wells,and even cause safety accidents.Taking several common intelligent well types as examples,the multi-pipe string inspection method for different types of intelligent wells based on transient electromagnetic(TEM)array was studied,and the high-resolution signal processing method was proposed,which can be used for window shape inspection in multi-branch well,optical cable inspection and positioning outside casing in fiber-optic sensing intelligent well,special structure inspection and asymmetric defect quantitative explanation for layered injection and production pipe strings.The main work and research results of the paper are as follows:(1)Against the issue that the transmitting–receiving distance(TRD)of the TEM intelligent well inspection system with single-transmitter single-receiver will affect the signal-to-noise ratio(SNR)and resolution,a maximum SNR method based on the TEM linear array was studied,which can reduce the impact of TRD on the received signal and improve the SNR of the TEM inspection system.On this basis,a sparse array-based multi-pipe string inspection method is proposed,which can solve the ill-condition problem of optimal weights and save computational costs.Finally,a TEM array signal processing method based on compressive sensing was proposed,which can effectively reconstruct target signals containing information about intelligent well pipes,eliminate the influence of TRD,improve the reliability of TEM systems,and provide a theoretical basis for optimizing and improving the performance of intelligent well multi-pipe string inspection systems.(2)A pipe string and window shape inspection method based on a TEM eccentric array was proposed to address the problem of incomplete pipe structure caused by sidetrack drilling at specific positions in multi-branch intelligent wells.On the basis of the magnetic field distribution of complex wellbore structure,the TEM eccentricity inspection model was established and the TEM array inspection system with azimuth recognition ability was studied.Furthermore,multiple eccentric sensors with spiral distribution are utilized to form an eccentric array to realize casing inspection in multiple directions.By comparing the TEM response of each array element,the window size and sidetracking angle calculation methods were studied,which provides a theoretical reference for the maintenance and advanced accident prevention of multi-branch intelligent wells.(3)For the issue of avoiding fiber-optic perforation caused by the placement of fiber optics outside the casing,a method for detecting and positioning fiber optics behind the casing based on a TEM circular array is proposed.Taking the distribution trajectory of fiber optics as the detection target,a TEM array detection system with high azimuthal resolution is studied based on the magnetic field distribution at different detection positions in optical fiber sensing intelligent well.Considering the size of the wellbore and tool design complexity,a circular giant magnetoresistance(GMR)sensor array is used to replace the traditional receiving coil,achieving high-resolution azimuth data acquisition around the wellbore,and a multi-channel data acquisition system based on a daisy chain for 32-channel GMR receiving sensors is designed.Also,a high-resolution identification method for fiber optics outside casing based on circular TEM array was presented to realize the highly efficient detection and positioning of fiber optics,providing important guidance for directional perforation avoiding fiber optics.(4)In response to the complex structure and asymmetric defect inspection problems associated with the large-scale application of layered injection and production wellbore,a cylinder array-based TEM system for online monitoring of multi-pipe strings in the production layer and high-resolution quantitative inspection of asymmetric damage were proposed.Based on the analysis of the string structure of the intelligent layered injection and production system,a simulation model for special structures such as downhole safety valves,Y connectors,and packers was established.On this basis,taking the advantages of a permanent downhole intelligent monitoring system equipped with single-core steel pipe cables,an online monitoring system for the multi-pipe string in production layers based on a TEM cylinder array was designed.Using the array azimuth data,a quantitative inspection method for the asymmetric defect was proposed to calculate the circumferential width and radial penetration depth,solving the problem of three-dimensional morphology inspection for asymmetric damage.It can provide theoretical guidance for the high-precision inspection of multi-pipe strings in layered injection and production intelligent wells. |
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