Electromagnetic noise emanating from petroleum exploration and development operations causes serious noise pollution, which not only affects the environment, people and work safety，but also strongly affected the instruments in drilling site, such as an electromagnetic measurement while drilling telemetry system. Therefore, deep understanding and knowledge of the characteristics and distribution of well site noise is of great interest for measurement instruments such as electromagnetic MWD telemetry system, Logging While Drilling, etc.
To address this problem, researchers from Xi’an Shiyou University Professor Keman Liu, Ma.Yinghao Zhang and Dr. Xiaoxin Wang designed a noise acquisition system to acquire the noise of drilling site for electromagnetic measurement while drilling telemetry system. The system generally consists of a low noise coupling transformer, a computer, acquisition card, tunable filter, low noise preamplifier among other components. The drilling site noise data were analyzed based on the Bootstrap method and Welch’s method, which employs the use of basic statistics to accurately obtain the noise level estimation of drilling sites thus improving the system performance. Being a computerized approach, the bootstrap method does not require a lot of experimental data to estimate the noise level and characteristics. This way, many questions can be answered with little modeling, assumptions, and analysis. Additionally, this method allows for low-cost analysis and evaluation of drilling site noise for solving practical drilling problems where process data cannot be obtained repeatedly. The work is published in the Journal of Petroleum Science and Engineering.
An operating oil field located near Northwest of China was chosen for demonstrating the feasibility of the bootstrap and Welch methods in obtaining drilling site noise data in different drill operations. According to the trial results, the system proved suitable for real-time well-site electromagnetic noise acquisition, signal process, analysis as well as display and storage. These insights also provided a basis for further improvement of the electromagnetic measurement while drilling system performance. Specifically, the well site drilling conditions and the noise generated by the industrial equipment significantly influenced the power spectral density of the well site noise. On the other hand, the noise in the extremely low-frequency band is a major consideration of the electromagnetic measurements while drilling systems. This showed the essence of modeling and characterizing the noise present in the extremely lower frequency band.
In a statement to Advances in Engineering, Professor Keman Liu said that there is still an open question what is the statistical law of well site noise and what factors are related to it. Bootstrap method is relatively simpler and offers application advantages in terms of cost and efficiency as compared to the conventional methods used in the estimation of noise statistical characteristics based on large samples. If we can use appropriate methods, such as bootstrap method, to accurately describe the distribution of the well site and establish the noise model, it will be a key contributor in enhancing the performance, optimization and system designs of various electromagnetic measurements while drilling telemetry systems for advancement of petroleum exploration and development technology.
Liu, K., Zhang, Y., & Wang, X. (2019). Applications of bootstrap method for drilling site noise analysis and evaluation. Journal of Petroleum Science and Engineering, 180, 96-104.