8882 meters! New record for deepest well onshore in Asia!
Well LUNTAN-1, which Anton provides Drilling technical services, created a new history once again:
On July 19th, the exploration well from China National Petroleum Corporation (CNPC) finished its well completion, and final total depth reached 8882 meters. It has become the deepest well onshore in Asia.
*Recently, the LUNTAN-1 well in tarim oilfield of CNPC entered the completion stage after drilling to 8882 meters
It broke the Asian onshore ultra deep well record of 8,588 meters
Anton provides drilling bits and is in charge of performance drilling and Measurement While Drilling (MWD) services for the well.
Anton team overcame the problem of poor drillability in 12 1/4" section (5504m - 7475.67m) for the Ordovician-Cambrian dolomite (Penglaiba formation in Ordovician system and lower Churitage group in Cambrian system are of siliceous and nodular chert, with compressive strength exceeding 200 MPa and poor drillability.) In order to meet the exploration and development requirements of Cambrian oil and gas reservoirs, 6-blades/8-blades customized PDC bits, non-planar tooth bits, composite bits and roller bits were carefully selected, while vertical drilling tools, double pendulum BHA, torsion impact generator, mud motor and high temperature resistant MWD tools were used to optimize overall drilling performance. The depth 7475.67m sets a new record for 12 1/4" section in Tarim basin. Particularly, the use of non-planar tooth bit and φ244mm high-efficiency mud motor in Yingshan formation (5534m - 6219m) brought a total footage of 685m in a single-run, 1.75 times longer than expected, and a ROP of 4.83 meters per hour, 2.41 times faster than expected.
As the well went deeper, fewer reference drilling and geological data could be found for 8 1/2" section (7475.67m -8882m). The large hole size, high temperature and high pressure from this ultra-depth all became problems. With its elevated drilling aggressiveness and shock resistance, non-planar tooth matrix bit X516 from Smith was selected. The life of single bit reached 200 hours, and the single-run drilling footage was over 300 meters, with an average ROP of 1.82 meters per hour, a 20% increase compared to adjacent wells. This greatly reduced the drilling trip time due to 8000m plus well depth. In order to ensure the quality of the borehole and drilling efficiency, high speed and low drilling pressure combination was adopted in the lower section. Drilling was carried out by monitoring the well inclination while drilling with high temperature resistant MWD system, and fully utilizing the pendulum effect of this BHA to control the inclination.
One of the big challenges Well LUNTAN-1 faced is its high temperature/high pressure, especially after 8000m. The static temperature at the bottom of the well exceeds 160 °C. In the section of 6598m - 8641m, the 175°C rated MWD system Anton team adopted, together with its various temperature control procedures, withstood this largest engineering test in many years. The system delivered a stable performance of 513.5 hours in a single-run. The real-time monitored well inclination was well controlled below 2°. All ensured the good quality of the borehole.
In such hostile down hole environment with limited reference data, the operation for Well LUNTAN-1 was carried out in a safe and efficient way, and kept refreshing regional drilling records in half a year time:
- On March 9th, the 12 1/4" section was completed at 7475.67m, refreshing the Tarim oilfield record;
- On May 2nd, the drilling depth of 8099m broke the record of Well KESHEN-21's 8098m as the deepest well in Tarim oilfield;
- On May 22nd, the drilling depth of 8589m broke the record of Well SHUNBEIYING-1's 8588m as the deepest well onshore in Asia;
- On June 8th, the drilled depth of 8848m was equivalent to hitting the foothill from the peak of Everest from the Himalayas;
- On July 19th, the final drilling depth stopped at 8882m, which makes Well LUNTAN-1 the deepest well onshore in Asia. It also sets the record for the deepest coring and deepest logging in Asia.
The successful drilling of the Well LUNTAN-1 is of great significance for exploring the effectiveness and hydrocarbon-bearing properties of the LUNNAN Lower Cambrian dolomite reservoir-caprock combination, advancing the progress of the deep strata exploration, and finding oil and gas succeeder reserves.