Ultra-deep well drilling technology helps high-quality exploration and development

With more and more exploration and development activities in deeper and more complex formations around the world, the scale of ultra-deep well drilling is expanding, and ultra-deep well drilling technology has become one of the important indicators to measure the level of drilling technology in a country or enterprise.

Since the end of the 1990s, Sinopec (5.980, -0.09, -1.48%) has successively explored and developed ultra-deep oil and gas fields such as Puguang gas field, Yuanba gas field, Tahe oil field and Shunbei oil and gas field, and solved ultra-deep wells under complex geological conditions. Drilling technology, supporting ultra-deep well drilling equipment and measuring instruments, the drilling capacity of ultra-deep wells is further enhanced, the drilling speed is increasing year by year, the drilling cycle is significantly shortened, and the deep stratum exploration and development is effectively guaranteed.

After 2008, Sinopec drilled more than 100 ultra-deep wells each year. Up to now, Sinopec has completed nearly 100 ultra-deep wells over 7,000 meters. Especially since 2018, the depth record has been continuously broken, marking the remarkable acceleration of Sinopec's exploration and development in the ultra-deep oil and gas field. It also marks that Sinopec ultra-deep well drilling technology has entered the world's popular.

Puguang Gas Field is the largest and most abundant large-scale marine gas-filled gas field that has been put into operation in China. It is the main gas source of the national Sichuan-to-East gas transmission project. The current annual production capacity of mixed gas is 11 billion cubic meters. The gas field has the characteristics of “four highs and one deep”. The average well depth is nearly 6,000 meters, the underground pressure is over 55 MPa, and the gas reservoir contains hydrogen sulfide and carbon dioxide. It is unique in the world. From the first exploration well P1 well drilled in November 2001, the last development well P104-3 well was drilled in September 2009, and the Puguang gas field lasted for 8 years, forming an ultra-deep well dominated by gas drilling and PDC+ screw composite drilling. Drilling technology, the average drilling cycle is 232.06 days, the mechanical drilling rate is 2.61 m/h, and various economic and technical indicators have reached world-class levels.

Yuanba gas field is the first ultra-deep high-sulfur reef atmosphere in China and the second largest acid gas field in China. The gas field gas reservoir has a depth of over 7,000 meters and is characterized by ultra-deep, high temperature, high sulfur content and multi-pressure system. It is one of the most difficult and risky gas fields in the world. Compared with the Puguang gas field, the Yuanba gas field gas reservoir is more concealed and buried deeper, making it more difficult to find. From the first well of the first exploration well Yuanba 1 in May 2006, the ultra-deep well drilling technology based on gas drilling, impregnated diamond drill bit + turbo compound drilling, PDC+torque impact generator drilling and PDC+ screw composite drilling was gradually formed. The average drilling rate of the exploration well is 1.75 m/h, and the average drilling period is 441.73 days. By 2016, the construction of the 4 million cubic meters/year mixed gas capacity in the two phases of the Yuanba gas field was fully completed.

Tahe Oilfield is China's first Paleozoic marine billion-ton oilfield and the largest oil and gas field of Sinopec in Xinjiang. Since the exploration and development of Tahe Oilfield, it has expanded from the first 2~3 blocks to the current 10 blocks. The well depth has expanded from about 5,000 meters to the current 7000 meters. After years of technical research, PDC+ screw has been formed. Ultra-deep well drilling technology based on composite drilling, anti-slanting straight drilling and 35 MPa high pressure jet drilling. In 2018, there were 10 straight wells drilled in the 12th district of Tahe Oilfield, with an average well depth of 6327.91 meters, an average drilling cycle of 59.61 days, and an average mechanical drilling rate of 8.10 m/h. The average drilling depth of the main body of Tahe Oilfield is 5869 meters, the average drilling cycle is 60.10 days, and the average mechanical drilling speed is 14.68 meters per hour. It can be seen that the ultra-deep well drilling technology in Tahe Oilfield has reached the world-class level.

The Shunbei oil and gas field is a new area, new field and a new type of major oil and gas breakthrough that Sinopec obtained in the Tarim Basin. The reservoir has a depth of 8,000 meters and is characterized by ultra-deep, ultra-high pressure and ultra-high temperature. Since 2017, the Northwest Oilfield has successively drilled a number of ultra-deep wells in the Shunbei oil and gas field, which has repeatedly set the Asian record and built an annual production capacity of 700,000 tons.

Gao Deli, an academician of the Chinese Academy of Sciences, and Luo Pingya, an academician of the Chinese Academy of Engineering, have commented that Sinopec has made important contributions to ultra-deep well drilling technology, making domestic ultra-deep well drilling technology a world leader.

From the current practice, the new drilling technology is undoubtedly an effective means to speed up the drilling of ultra-deep wells. It is necessary to continue to strengthen the research, break the monopoly of foreign technology, and reduce costs with independent and efficient technology. At the same time, in order to improve the speed of drilling in a region, in addition to adopting a suitable well structure, the most suitable drilling technology should be selected for different strata in different blocks, so that the speed-up effect can be achieved with half the effort.