Experimental Study on the Transmission Law of Ultrasonic in Mud

In the process of oil and gas exploitation, the problems of wellbore instability and collapse seriously restrict the efficiency and safety of drilling and completion engineering. Ultrasonic borehole imaging technology while drilling has the advantages of accurately reflecting borehole shape, identifying fractures, pores, bedding and other characteristics. It can be used for real-time monitoring and evaluation of borehole engineering conditions and quality while drilling, which can effectively reduce drilling risks and costs, improve drilling efficiency and reservoir drilling rate. In order to develop ultrasonic borehole imaging tools while drilling and accurately interpret the ultrasonic images, this paper researches the transmission law of ultrasonic in mud, builds and designs the experimental device and experimental platform, formulate the experimental scheme. Laboratory simulation experiments were carried out to analyze the effects of different measurement distances, different mud density, different temperatures and different objects on the travel time and echo amplitude of ultrasonic and the main factors affecting the imaging effect. The experimental results show that: (1)The ultrasonic travel time increases linearly with the increase of measurement distance, increases with the increase of mud density, and increases slightly with the increase of transmission medium (water) temperature; (2) The ultrasonic echo amplitude decreases exponentially with the in-crease of measurement distance, decreases exponentially with the increase of mud density, and increases slightly with the increase of trans-mission medium (water) temperature; (3) Ultrasonic travel time information can be used for well diameter measurement and wellbore shape identification; (4) The ultrasonic echo amplitude information can be used to identify and image the characteristics of wall cracks, pores and holes; (5) Ultrasonic can be applied to the measurement and imaging of high density oil/water-based mud. The above conclusions lay a solid theoretical foundation for the independent research and development of ultrasonic borehole imaging tool while drilling.