On May 4, 2015 (March 16, 2015 lunar calendar), our country mastered two advanced technologies of rotary steerable drilling and logging-while-drilling in oil and gas fields. Directional drilling and measurement-while-drilling/logging-while-drilling schematic diagram of our country mastered two advanced technologies of rotary steerable drilling and logging-while-drilling in oil and gas fields, which can drill thousands of meters below like a "3D gluttonous snake". On May 4, 2015, our country's self-developed rotary steerable system and logging-while-drilling system completed drilling operations in the Bohai Sea. These two technologies can guide drills like a "3D gluttonous snake" to freely travel through hard rocks thousands of meters underground and accurately hit oil reservoirs. These two technologies represent the highest level of drilling and logging technology in the world today. Our country has broken the international monopoly in these two technical fields and become the second country in the world to have both technologies. China National Offshore Oil Corporation (referred to as "China Offshore Oil") has also become the fourth in the world and the first domestic enterprise to have both technologies. At 5:00 am on May 4, after 63 hours of continuous operation, with the Bohai No. 9 drilling platform, the instrument drilling tool successfully completed the operation task and returned to the sea from 3,000 meters underground, marking that our country's self-developed rotary steerable drilling system and logging while drilling system are fully capable of offshore operations. According to CNOOC news, the company's self-developed rotary steering system Welleader? and Drilog?, a logging-while-drilling system, recently completed the offshore operation of a well in the Bohai Sea. This marks that our country has broken the international monopoly in the field of directional drilling and logging-while-drilling technology in oil and gas fields, and can independently complete the production needs of offshore "cluster wells" and complex oil and gas reservoirs, which is expected to greatly reduce the comprehensive cost of domestic oil and gas field development. All along, oil and gas field development is like doing a "calculation problem" of timeliness and cost, that is, how to complete drilling services with the smallest cost and the fastest speed when the location of underground oil and gas reservoirs is known? In other words, if you want to extract "high-quality and cheap" oil and gas resources, you must complete the largest range of reserves with the least number of wells and achieve the shortest drilling cycle with the least number of drilling starts. Faced with the difficulty of "accurate calculation", oil companies have invariably opted for directional drilling technology that can travel "horizontally" in the formation. Unlike ordinary drilling operations, directional drilling operations do not allow the drill bit to reach the target layer "straight", but require the drill bit to be able to drill deep in the formation at a designed slope until it hits the "bullseye" of the underground reservoir up to several kilometers deep. At present, more than 40% of the world's directional wells are drilled using rotary guidance systems. The advantage is that it can control the direction of drilling in real time, and realize the adjustment of the running trajectory of the drilling tool similar to the "3D version of Snake", so that one-stroke drilling penetrates the target formation distributed in the "three-dimensional" area - even allowing the 0.2-meter diameter drill bit to pass through the thin oil layer of 0.7 meters laterally or diagonally, and realize the long-distance operation of "lateral" movement of 1000 meters in one-stroke drilling. This kind of precision guidance is of great value in reducing development costs and maximizing the development of oil and gas field resources. If the rotary guidance system is compared to the "scud" in the drilling system, then the logging system while drilling is the "clairvoyant" installed on it. The rotary guidance system can complete the operation thousands of meters underground, which cannot be separated from the "navigation and guidance" of the LWD system. The LWD system can feed back the downhole geological data "along the drilling route" to the surface at any time, and the logging engineer completes the real-time information processing and command transmission, which is equivalent to installing a "clairvoyant" for the downhole equipment. The two systems work side by side, enabling directional rotary drilling of the whole well section, real-time adjustment of the wellbore trajectory, and measurement of downhole environmental parameters, which can greatly improve the operation efficiency and reduce the engineering risk. It is a "trump card" for the operation of difficult directional wells such as ultra-deepwater, horizontal wells, and large-displacement wells. However, due to the difficulty of research and development, these two technologies have been monopolized by three oilfield technology service companies in the United States for many years. At present, more than 40% of the world's directional wells are drilled using rotary steering systems. According to the statistics of the global operation volume, these two technologies brought at least about 20 billion US dollars of revenue to the relevant companies in 2014. In 2008, with the support of the "National 863 Plan", CNOOC's holding company, CNOOC Oilfield Services Joint Stock Company, began to independently develop two sets of rotary steerable drilling and logging while drilling systems. After arduous exploration, it finally broke through the technical bottleneck and formed a trademark, system technology and equipment system with independent intellectual property rights. On November 18, 2014, CNOOC's independently developed rotary steerable drilling and logging while drilling system jointly completed the first offshore operation. This marks that our country has broken the international monopoly in the field of oil and gas field drilling and logging cutting-edge technology, which is expected to greatly reduce the development cost of domestic oil and gas fields, and add a heavyweight weight to COSL's participation in the international high-end oilfield technology service market competition. In the Bohai operation completed yesterday, the two systems drilled 813 meters of directional well section in one trip, successfully hitting three targets of 1613.8 meters, 2023.28 meters and 2179.33 meters. The maximum well inclination is 49.8 °, and the minimum bull's-eye distance is 2.1 meters, which fully proves that the two systems have the ability to operate offshore. Li Yong, CEO and president of COSCO Oilfield Services joint stock company, said that in recent years, the company has continued to increase investment in science and technology, and a large number of self-developed scientific and technological achievements have emerged. The success of the joint offshore operation of rotary steerable drilling and logging while drilling marks that the company has become the fourth in the world and the first company in China to own both technologies. In the future, the company will be committed to the industrialization and application of the two technologies to meet the urgent needs of our country's oil industry for high-end technologies, and also to "go out" for our country's oil companies to participate in the international high-end oilfield technology service market competition.