###### Abstract  
Based on a comprehensive analysis of the existing methods for measuring adjacent well distances, along with their advantages and disadvantages, this study employs theoretical analysis, simulation experiments, and other comprehensive research methods to investigate a distance measurement method based on current excitation. In response to the need for measuring and controlling the connection of relief wells, a method utilizing dual-electrode current excitation during drilling is proposed. This approach facilitates synchronous excitation measurements while drilling, significantly reducing both time and costs while ensuring safety and efficiency, making it particularly suitable for the connection operation of relief wells that involve safety risks. Firstly, this paper establishes a drilling with measurement model corresponding to the excitation mode, which derives the calculation formulas for the target casing current amplitude attenuation, as well as the induced magnetic field distribution within the formation. Additionally, it provides the calculation methods for determining the target well distance and azimuth direction. Lastly, the impact levels of various key factors are verified through numerical calculations and simulation analyses, which confirm the correctness and effectiveness of this distance measurement method. The findings from this research establish both a core theoretical foundation and a technological basis for the real-time measurement of adjacent well distances during relief well operations. complex structure well; dual-electrode current excitation; adjacent well distance; Matlab simulation 2024202024  
With the continuous improvement and progress of measurement methods and technologies, foreign countries have applied for a variety of new ranging method patents [1,2]. A series of commercial electromagnetic ranging tools, such as the Magnetic Guidance Tool (MGT), Rotating Magnetic Ranging System (RMRS), Single Wire Guidance (SWG), and WellSpot, have been developed to accurately detect the relative position between the drilling well and the drilled well. These advancements address the problems of the connection of relief wells, cluster wells anti-collision, SAGD double wells spacing control, and the connection of double horizontal wells. The drilling well cable unipolar current excitation ranging method was proposed by [PERSON] et al. [2,3]. This access-independent active ranging method does not require any excitation or measuring tools to be placed in the target well; all the current injection devices and measuring tools are located in the drilling well. As a result, it offers advantages such as a low safety risk and a short operating time [3]. The drilling well current excitation ranging method  
In order to achieve the real-time measurement and control of the inter-well distance, as well as to provide real-time adjacent well distance information during drilling, and save operation time, scholars such as [PERSON] have proposed an access-independent current excitation measurement while drilling (MWD) method [5,6]. In this method, the current source device and the insulating nipple are installed on the drill collar of the drilling well. During the drilling process, the current output by the current source uses the metal shells above and below the insulating nipple as the positive and negative electrodes, with the ground layer around the head of the hole where the drilling tool is located serving as a conductor [7,8]. This forms a similar elliptical spherical current loop in the formation. If there is a casing or drilling tool in nearby formations, then the injected currents will flow through these highly conductive objects, generating an induced magnetic field in the surrounding formation [9,10]. A high-precision magnetic field detector installed at the bottom of the Bottom Hole Assembly (BHA) in the drilling well can detect this magnetic field and obtain distance and orientation information for the target wells [11,12].