Application of logging technology in petroleum exploration

[Abstract] China's traditional oil logging technology has low resolution and poor intuitiveness, and it is easy to lead to multiple solutions. It can not meet the needs of modern oil logging. Based on this, exploring a new type of oil logging technology to continuously improve the quality of oil logging in China is of great significance to the development of China's oil logging industry.

Key words: sensor; logging technology; oil logging

At this stage, traditional oil logging technology has been difficult to meet the needs of oil logging. Faced with a large number of oil exploration projects, deep detection, high measurement accuracy and high-resolution oil logging technology emerged. After long-term development, petroleum logging instruments have undergone five renewals. At present, the oil logging instruments used in China's oil fields are the fourth-generation CNC logging tools and the fifth-generation imaging logging tools.

1 Common logging technology

1) Electrical logging. Electrical logging is one of the commonly used techniques in petroleum logging. It mainly refers to the generation of current to the ground through a logging tool downhole, which effectively measures the potential of the ground and finally obtains a logging of formation resistivity. the way. Common methods such as formation dip logging, induction logging and lateral logging, and logging of ground currents to the natural potential of the formation are all electrical logging techniques.

2) Acoustic logging. Acoustic logging is mainly a kind of petroleum logging technology that measures formation specificity and wellbore engineering conditions by measuring the acoustic properties of the annular wellbore formation, including various logging methods such as sound amplitude logging and sound velocity logging. In general, the use of acoustic measurement can clearly reveal the specificity of the wellbore. Such logging techniques are generally used to derive original and secondary porosity, void pressure, fluid type, fracture orientation, etc. Acoustic imaging logging technology is A petroleum logging technology based on the full use of computer image processing technology, which digitizes various signals received by the transducer and processes the preprocessed image into a converted image.

3) Nuclear logging technology. Nuclear logging technology is mainly based on the physical properties of formation rocks and rock pore fluids. It is also known as radioactive logging technology. Nuclear logging technology is divided into the following two categories based on radioactive sources, measured radioactive types or physical properties of rocks: gamma logging, nuclear logging methods based on gamma radiation; neutrons Logging, a nuclear logging technique based on the study of the interaction between neutrons, rocks, and fluids in their pores. The two main nuclear logging techniques include density logging, natural gamma logging, natural gamma spectroscopy logging, and neutron porosity logging.

4) Cable formation test logging technology. Cable formation test logging technology is also a very common oil logging method, which is mainly used to verify the fluid properties in oil and gas exploration work and to effectively estimate the formation productivity. Cable formation testing technology is fast, economical, and simple compared to conventional drill pipe testing. On the one hand, the quartz pressure sensor of the cable formation test logging technology can accurately and quickly measure the pressure and temperature changes of the formation; on the other hand, the multi-detection tester used in this logging technology can directly measure the formation. Radial and vertical permeability. In addition, techniques such as fluid resistivity measurement and spectral analysis downhole can also effectively determine the type of fluid. In general, cable formation testing is used for the construction of single well pressure profiles, the calculation of fluid density, the determination of gas, oil, and water interfaces, and the estimation of effective permeability of formations.

5) Imaging logging. Image logging technology has the characteristics of high resolution and large amount of data collected. The measurement results can be expressed in the form of images by computer, which is more intuitive. The main equipments that make up the imaging logging system are imaging logging tools, nuclear magnetic resonance logging tools, digital imaging systems, computer workstations, and the like. Image logging technology is more adaptable than conventional logging technology. Its main instruments include: array sensing, well sound wave, array orientation, nuclear magnetic resonance and multi-pole array acoustic waves.

2 Application of sensor technology in oil logging

Geophysical logging is a branch of applied geophysics that is the discipline that solves geological and engineering problems using the principles of physics. Because logging has high density, high resolution, good longitudinal continuity, and comprehensive information and technical advantages, it has become the main body of stratigraphic evaluation, and is an indispensable key technical means for oil and gas resource evaluation and reservoir management. Its geological and engineering applications cover the entire process of oil and gas exploration and development. With the increasing difficulty of oil and gas exploration and development and the development of logging technology, the application of logging technology has gradually evolved from the identification and evaluation of traditional single well oil and gas layers to the reservoir description and evaluation of well logging. It is used more and more widely in formation evaluation, geology, drilling and oil recovery engineering.

1) Application of fiber optic sensors in oil logging. Optical fiber sensors are born with light communication technology. Due to electromagnetic interference, they need to withstand extreme conditions, including high voltage, shock, vibration, high temperature, etc., which can accurately measure well and wellbore environments. Fiber optic sensors are a kind of distributed measurement. Measure spatial distribution and profile information. At the same time, the fiber optic sensor has a small cross section, a short shape, and a small space. Laser sensor technology is a sensor that combines laser technology and fiber technology to measure in mud, crude oil and other wells. At the same time, it utilizes photoinduced loss and luminescent physical effects to develop different nuclear detection energy levels and develop sensitive probes. Stratigraphic evaluation: analysis of rock properties, determination of stratigraphic interface, calculation of mineral composition of rock strata, mapping of lithology, calculation of reservoir parameters such as porosity and permeability, comprehensive evaluation of reservoirs, division of oil, gas and water layers, and evaluation of production capacity .

2) Application of network sensor technology in oil logging. In petroleum logging, the network is an integration and development, mainly showing the development of arrayed probes, collecting imaged ground, reservoir solutions, and information sharing to promote real-time. According to the standard, the network logging combined fast platform can be improved by NMR, acoustic imaging, formation testing and other technologies, and can be integrated into network logging technology. It is beneficial to evaluate the dynamic analysis of oil and gas water, logging identification, rock mechanics and logging address. Logging technology is gradually changing. The main features of Internet technology are information sharing and reliability. Downhole instruments provide reservoir solutions and observation information.

3) Logging while drilling. Such a logging method refers to a logging method in which a logging tool is installed at a location close to the drill bit, and various information of the formation is simultaneously measured during the drilling process. The logging while drilling can better control the drilling direction by measuring the direction of the inclination angle of the formation, drilling pressure and the like. Using this method to measure the natural potential, resistivity, density, neutron and nuclear magnetic, acoustic time difference and other indicators of the newly drilled formation, the above measurement method not only effectively avoids the measurement results of downhole conditions such as mud intrusion and wellbore expansion. The impact of the well can provide well information for the formation to better guide the drilling orientation. For logging in difficult, horizontal and high-angle wells, LWD can show its unique advantages, which can provide operators with scientific drilling basis and provide operators with more detailed wellbore. Surrounding information, such as stress conditions around the wellbore, geosteering, etc., to help operators perform formation evaluation more effectively.

4) Dual lateral logging. The dual lateral logging technique mainly uses the current shielding method to force the main electrode current to be focused into a horizontal current beam perpendicular to the well axis and into the formation laterally, so that the shunting effect of the well and the influence of the low resistance layer on the current gradually cut back. The above methods can reduce the influence of the wellbore and the surrounding rock on the logging result, and can solve the problem that the common logging technology cannot solve while realizing the effective and effective reflection of the formation resistivity change.

3 Conclusion

With the development of science and technology in China, China's oil logging technology faces more development opportunities and more severe challenges. Based on this, in the development process of petroleum logging technology, scientific research and operators should continuously strengthen the research of relevant theoretical foundations, and conduct more in-depth practical research under the condition of complete theory, while continuously improving the ability of independent innovation. To achieve simplification, precision and rapidization of China's petroleum exploration.

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