The first ultra-deep marine shale gas exploration well in China was successfully completed
On Sept. 2, the exploration South Branch deployed a marine shale gas well-Ding 2HF well on the northeastern tectonic belt of Lintan-Dingshan in southeastern Sichuan. The well was drilled with a total drilling depth of 5,700 meters. From the current data Look, this is also the first ultra-deep unconventional horizontal well. The well below the Silurian Longmaxi Formation lower shale gas layer for the purpose of exploration wells in the Longsheng 2 well after drilling high-quality shale gas wells, the horizontal well drilled in the original wellbore. The well was designed to well 5655.24 meters in depth and 4010 meters in depth at the side drills. Drilling was conducted on July 9 and drilling at a level of 1,034 meters was completed in only 55 days.
The drilling of the Longsheng-2 well in the early stage confirmed that there is shale gas development in the Wufeng-Longmaxi Formation and the measured gas content in the field is relatively high, which is similar to that of the Jiao-1 Well, and is another area where the Longmaxi Formation shale oil and gas exploration business Find the most favorable areas. In the whole well, a total of 1106 meters of oil-gas display layers were discovered in the whole well. Four layers of 1056-m thick high-quality shale gas reservoirs were found in the lower part of the Longmaxi Formation of the main target formation. The maximum total hydrocarbon content during drilling was 89.56% Above 22%, the fractures of the rich TOC mud (page) generally develop, the gas measurements are high and the post-anomalies are active and strong, indicating that the shale gas exploration in the deep and ultra-deep marine shales in the Sichuan Basin and its peripheral areas has good prospects for development.
Exploration of the South Branch in the well structure design to break the conventional shale gas wells horizontal section A target before the next layer of casing before the horizontal section of drilling conventional thinking, Pipe, drilling of 91/2 "wellbore 1690m long", this is the first case of shale gas drilling in China.Our well is a typical "three high" well, the geological structure is complex, there are multiple sets of pressure system, the main gas reservoir It has the characteristics of high temperature, high pressure and high sulfur leakage. It has the problems of large frictional torque, poor stability of directional tool surfaces, high failure rate of directional tools, and difficulty in well trajectory control. It is a world-class engineering problem. During the directional construction, technicians adjust the drilling parameters in time according to the formation, lithology, and drilling time variation, and overcome the problems of long horizontal section length, high temperature, high grinding temperature and difficult sliding drilling in the late stage of construction. The use of Atlas torque impactor with efficient PDC + screw orientation technology, the horizontal section to give full play to composite drilling, LWD tracking while drilling technology, and to create a combination of ultra-deep shale gas drilling day Footage highest 178 meters, the highest single bit has drilled only 724.7 meters, the average single-bit only mechanical penetration rate up to 6.81 m / h and many other indicators.
Because it is the use of the original Longsheng 2 wells and wellbores for construction, reducing the pre-drilling and vertical section of the construction, saving about 300 days cycle, saving more than half the cost. At present, Ding page 2HF well is trying out the gas preparation.
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