On the challenges of logging technology

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Talking about the challenges faced by logging technology

logging technology is a technology while drilling in the process of oil and gas exploration and development. Nowadays, most of them are metal materials, which play an increasingly important role in establishing formation profile, discovering and evaluating oil and gas reservoirs, guiding engineering safety construction and so on. Geological logging is the fundamental task of logging, and engineering logging and information service are the expansion of logging. But with the global warming potential value increased by 130% Compared with other related majors, the development of logging technology is relatively slow. At present, due to the increasing difficulty of exploration and development and the technological innovation of drilling technology, new challenges have been put forward to logging technology

first, the challenge of increasingly complex oil and gas geological conditions

at present, 39% of the remaining oil resources and 57% of the remaining natural gas resources on land are distributed in the deep layer. Moreover, the remaining oil and gas resources in the complex surface environment area account for a considerable proportion. 27.26% of China's onshore oil resources are distributed in mountainous, Loess Plateau, desert, beach and swamp areas. 85.1% of the national natural gas resources are distributed in sea areas, deserts, mountains, Loess Plateau and plateau areas with complex geographical conditions. This not only increases the difficulty of exploration and logging in depth and breadth, but also because these resources have strong concealment

with the change of exploration objects, the geological conditions of the old oil and gas fields are becoming increasingly complex. The target layer has the characteristics of high mud, high calcium, low porosity and permeability, thin interbedding, strong heterogeneity, high temperature and high pressure, high stress, salt gypsum layer and so on. The difficulty of discovery and evaluation of oil and gas reservoirs is increasing, such as special lithology and subtle oil and gas reservoirs, low-pressure and low-permeability oil and gas reservoirs, gas reservoirs, oil reservoirs, buried hill oil and gas reservoirs, heavy oil reservoirs, etc. in the old areas with relatively high exploration degree, has become the main direction of exploration. The logging industry plays an increasingly important role, requiring the logging profession to have relatively perfect characteristic technologies and theoretical methods for different types of oil and gas reservoirs, However, the current logging technology can not meet the demand to a certain extent

in addition, with the continuous development of the old oil and gas fields and the increasing comprehensive water cut, it has become very difficult to use conventional analysis methods to judge the degree of water washing and water flooding of the oil layer, especially in the small layer, due to the large changes in lithology, serious heterogeneity, and extremely uneven degree of water washing, which makes it very difficult to stabilize oil and control water and improve oil recovery. How to play the role of logging data and provide scientific basis for targeted technical measures and enhanced oil recovery is a difficult problem for logging workers

exploration and development targets are increasingly refined, which puts forward higher requirements for logging. We should not only find oil and gas indications in time and accurately, but also interpret and evaluate oil and gas reservoirs and oil and gas properties in time and accurately. The logging industry has not formed a complete technical theoretical system, and most interpretation and evaluation technologies only stay in a small area and at the level of experience, so they lack the momentum for development and long-term technical development direction

marine deep oil and gas exploration and development put forward new requirements for logging technology. The formation has the characteristics of relatively old oil-gas reservoir, large buried depth of the target layer, large formation dip angle (common in high and steep formations), complex formation lithology and pressure system (such as salt gypsum layer, glutenite layer, fractured reservoir, abnormal pressure layer), tight reservoir lithology, strong oil-gas heterogeneity, local high sulfur content, CO2 content, etc. It brings challenges to logging, such as difficult identification of marine lithology, difficult determination of complex structures, difficult identification of faults, difficult discovery and collection of oil and gas reservoirs, difficult evaluation of reservoirs, difficult determination of favorable fracture and cave sections, difficult prediction and monitoring of formation pressure, and difficult prediction of Engineering anomalies

II. Challenges in the development of drilling technology

in recent years, drilling technology has developed rapidly, drilling technology has changed greatly, directional wells and deep exploration wells have increased, and underbalanced drilling, slim hole drilling, air drilling, high-pressure jet and other technologies are more and more widely used, These complex drilling techniques bring new challenges to logging technology:

logging technology under the conditions of horizontal well drilling and extended reach well drilling

with the deepening of oil field exploration, the exploration object has also changed from simple structure to complex fault block structure. In order to improve the utilization rate of a single well, we should find or drill through oil and gas reservoirs as much as possible, making extended reach wells and horizontal wells more and more valued. In recent years, China's horizontal well drilling technology has developed rapidly, and the number of wells drilled has increased year by year, gradually forming a relatively perfect drilling and completion supporting technology. With the wide application of horizontal well drilling, the technology of extended reach well has also developed rapidly. However, compared with vertical wells, the drilling construction of extended reach wells and horizontal wells has considerable risks, such as the increase of drilling accidents and the difficulty of drilling for geological purposes. At the same time, the drilling of highly deviated extended reach directional wells and horizontal wells also brings great difficulties to the field logging work: for example, the mixing of rock cuttings is more serious, the representativeness becomes worse, causing difficulties in lithological description and the difficulty in the homing of oil and gas display layers, The formation lithology and physical properties cannot be accurately reflected during drilling; Moreover, in order to reduce the friction of drilling tools in extended reach wells and horizontal wells, organic drilling fluid or oil mixed mud is often used, which will greatly affect the role of fluorescent logging and gas logging. All these factors will reduce the acquisition quality of logging data, the accuracy of profile homing and the coincidence rate of reservoir interpretation, and weaken the guiding role of field logging on drilling

logging technology under the condition of underbalanced drilling

underbalanced drilling is a new drilling technology developed in the United States and Canada in the early 1990s. Underbalanced drilling includes gas drilling, foam drilling, and underbalanced drilling with ordinary mud (water-based and oil-based mud with density less than formation pressure gradient). At present, it has been widely used abroad and is in the ascendant in China. Many wells such as Wengu 3 well and bu 1-34 well in Zhongyuan Oilfield have been adopted. This technology can not only minimize the damage to the reservoir and find low-pressure, low porosity, low permeability and subtle oil and gas reservoirs to the greatest extent, but also avoid vicious lost circulation and improve the drilling speed, so as to improve the comprehensive benefits of drilling. However, it also brings great influence and new challenges to the comprehensive logging work, such as the difficulty in the collection and identification of cuttings samples, the difficulty in the judgment of oil and gas reservoirs and data collection, and the difficulty in the monitoring and prediction of Engineering anomalies

logging technology under ultra deep well drilling conditions

since the 1980s, the drilling depth of Tarim Basin in China has exceeded 5000 meters, and later more than 6000 meters of wells are common. On July 27th, 2006, the drilling of Tashen well 1 was completed by North China Petroleum Bureau, and the drilling depth reached 8408m. At present, the technology of ultra deep wells and even ultra deep horizontal wells in China has been relatively mature. Ultra deep wells are prone to drilling accidents such as drilling tool leakage, pump stabbing, plugging, water hole dropping, and drilling tool resistance, jamming, slipping, broken drilling tool, gear dropping, shaft wall collapse, etc., which make it difficult to predict engineering accidents

changes in drilling engineering technology have changed the material basis relied on by logging work, such as mixed cuttings (even mixed with a large amount of additives, crude oil, industrial oil, etc.), fine cuttings (even powder, dust), oil and gas loss, and insignificant changes in drilling time, etc. The development of drilling technology has brought great challenges to the identification of logging lithology, layered naming, identification of oil and gas, evaluation of oil and gas reservoirs, and coring

third, quantification, digitization and informatization put forward new requirements for logging technology

people are used to using quantitative data, which can accurately and intuitively express the characteristics of things in the form of a few numbers or curves, and can also accurately compare different things. Most of the logging data are qualitative, many are descriptive, the data types are very complex and diverse, and the comparability of logging data in different regions, different wells and different horizons is poor. In addition, in the face of complex and diverse logging data, how to use mathematical statistical calculation and calculation, of which 363 gigawatts (39%) will come from modern digital technology means such as Chinese computer processing to obtain quantitative evaluation results, is a major technical problem at present

logging is not only a direct means of oil and gas discovery, but also the first-hand data of reservoir evaluation. Timely and accurate logging evaluation will provide strong technical support for reservoir protection, determination of well completion plan, testing and layer selection, determination of perforated well section and other reservoir engineering operations. However, at present, the level of interpretation and evaluation of the reservoir by logging is low, and most of them still stay at the level of naming the oil-bearing level of the reservoir rock, so it is difficult to make an accurate quantitative evaluation of the reservoir fluid properties. At present, the evaluation of reservoir by logging mainly depends on experience, without systematic theoretical support. Logging only answers the question of whether there is oil and gas, and there is no good answer to the questions of whether there is oil or gas, how much, and whether it can be moved. Logging is only playing the role of discovery

as the drilling site provides important first-hand data for exploration and development, major foreign oil companies attach importance to the use of drilling site information. At present, more than 20 countries and regions abroad carry out remote transmission of well site data. Transmission standard: wits standard. Transmission mode: satellite is mostly used. Facing the opportunities and challenges brought by foreign information management, Chinese oil enterprises are also actively deploying and implementing it. In recent years, domestic oilfields have begun to establish their own well site data sharing platforms and accumulated a large number of data resources. The technical standards adopted by these platforms are different, and the content of the database has the characteristics of each oilfield. In terms of data remote transmission, cdmagprs mode is mostly used for general wells, and satellite communication mode is used for key wells or communication blind areas. Compared with foreign countries, the domestic well site information team pointed out the following problems in the paper released in July: the collation of oilfield data is not standardized, and the database standards and platform technical standards are not unified; The data interface of comprehensive logging instrument is not unified; The phenomenon of emphasizing construction and neglecting application exists to varying degrees

IV. new requirements of Engineering anomaly detection and prediction for logging

at present, 90% of the downhole anomaly detection of comprehensive logging services drilling engineering, but there are still problems that are difficult to quantify. With the more mature application of comprehensive logging engineering parameters, as well as the gradual maturity and application of technologies such as downhole real-time ground pressure monitoring, drilling tool vibration while drilling, gas drilling downhole combustion and explosion detection, it will provide a more accurate and reliable basis for improving the detection and prediction methods of abnormal conditions under various geological and engineering conditions. It will play an irreplaceable role in further embodying the role of logging engineering and expanding the service scope of logging technology

v. economic development poses challenges to logging

logging engineering, as an important part of oil and gas exploration and development, has been in a marginalized position for a long time, has not received due attention, and the price system of logging engineering is unreasonable. On the other hand, with the increasing difficulty of exploration and development, various equipment, technical measures, safety and environmental protection facilities are increasing. All logging companies have low employee income and serious brain drain, which affects the stability of the workforce and restricts the development and technological progress of logging engineering

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