Abstract
Accurate measurement of drill bit position and direction is the main technology to realize automation and intelligence in oil drilling field. In recent years, with the rapid development of complex drilling technologies such as high deviation wells, directional wells and horizontal wells, higher requirements have been put forward for measurement technology, especially for real-time monitoring of bit attitude and position during the drilling process. Therefore, for the past few years, the measurement while drilling (MWD) system has been widely recognized and developed rapidly in precision targeted drilling. among them, strap-down inertial navigation system (SINS) consisting of accelerometer and gyroscope is the key of down-hole measurement while drilling. To solve the problem of accumulated errors in SINS, in this paper, a positioning error correction method based on kinematic constraint-aided (KC) SINS zero velocity updated (ZUPT) model is proposed. Firstly, based on the acceleration and angular velocity information measured by SINS, empirical mode decomposition (EMD) and wavelet de-noising reconstruction are performed for MWD signals. Secondly, the static detection model of the drill bit is established by using the reconstructed signal. Thirdly, using drilling technology to analyze the motion attitude of the bit, the KC model of the down-hole bit is established. By analysis the alternating effect of the KC model and the ZUPT model in the process of the bit movement and stop, the ZUPT model of the SINS is established. Finally, experimental verification is performed by building a drilling platform. The experimental results show that the maximum positioning error of the proposed positioning model is 0.15 m within 300 s. Comparing with a single KC model and a single ZUPT model, the bit positioning accuracy is improved to 92.6%, which effectively suppresses the original cumulative error, and verifies the feasibility of the proposed method.
Highlights
Petroleum is called ‘‘black gold’’ which belongs to fossil fuel and is non-renewable [1]
Aiming at the problem that drilling bit cannot be positioned accurately in real time during drilling, the measurement characteristics of strap-down inertial navigation accelerometer and gyroscope in measurement while drilling (MWD) system are analyzed, and an empirical mode decomposition (EMD) wavelet de-noising algorithm based on measurement limit while drilling is proposed
In order to verify the effectiveness of the proposed method, simulation drilling is used to verify the proposed positioning error correction strategy
Summary
Petroleum is called ‘‘black gold’’ which belongs to fossil fuel and is non-renewable [1]. Since the late 1960s, MWD technology has developed rapidly in the field of drilling [15] It is used for real-time formation evaluation and drilling geological guidance. It shows economic and technical advantages in controlling bit trajectories in horizontal wells or highly deviated wells and complex logging environments [16], [17] In this case, the MWD system based on micro-inertial measurement unit has been developed, and widely recognized in oil field exploitation because of its advantages of low cost, small size, long life, high integration, strong impact resistance and high reliability [18]. DeSanto et al applied KC algorithm to ship navigation data processing [29] These researches not put forward the corresponding technical scheme for precise positioning a bit after de-noising of down-hole while drilling signal. This paper proposes a de-noising algorithm based on EMD and wavelet packet reconstruction for down-hole measurement signals while drilling, and uses the reconstructed signals to alternate KC and ZUPT models to achieve dynamic real-time positioning of down-hole drills
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