The casing reshape technology independently developed by our company is a new and efficient casing shaping technology. Its tools consist of pressurization system, anchoring device, hydraulic cylinder, expanding tube, and rolling balls. When it works, the surface pump provides hydraulic power, and after pressurization, a fulcrum is established inside casing; at the same time, the reshaping balls crush the deformed section of the casing repeatedly. In this way, the deformed section of casing is restored.
2.There is no impact on the geometric shape of casing. The casing can restore its inherent roundness;
3.Apply to most casing deformations; the minimum operating channel is 40mm;
4.Short performance time, which can reduce downtime;
5.The reshaping ability is strong, and the requirements for equipment configuration is low;
6.This technology can be applied to horizontal wells.
1. High-Pressure Sealing of Fracturing Casing — Pre-Fracture Sealing for Shale Gas:
(1)Pre-Construction Issues: A full wellbore pressure test at 90.00 MPa showed a pressure drop to 61.00 MPa after 30 minutes, a reduction of 29.00 MPa (32%).
(2)Technical Challenges: The seal must withstand repeated pressure and tension fluctuations caused by wellbore fracturing.
(3)Operations：Casing to 1200m, inject 5 m³ of sealing agent A using reverse circulation, and replace with clean water to 1200m. After removing the coiled tubing, pressurize with a fracturing truck to 93 MPa, hold for 10 hours, with a pressure drop of 0.6 MPa every 30 minutes.
Relieve pressure, open the wellhead, and inject 5 m³ of sealing agent B using reverse circulation to 1200m, replacing with clean water. After removing the coiled tubing, pressurize again to 93 MPa, hold for 10 hours, with a pressure drop of 0.3 MPa every 30 minutes.
Relieve pressure, open the wellhead, and case to 1400m. Replace plugging agents and perform a full wellbore clean water pressure test at 90.50 MPa. After 30 minutes, pressure drops from 90.50 MPa to 90.24 MPa (0.26 MPa/30 min). Pressure test passed.
In 2007, the first well field test was successful. By the end of April 2021, 916 wells had been shaped in 10 oilfields such as Shengli, Zhongyuan, North China, Puguang gas field, Nanyang, Jiangsu, Karamay, Dagang and Qinghai, and 763 wells were successfully shaped, with a success rate of 83.3 %. In the past three years, the success rate of field construction reached 95.1%.
Since the successful development and field application of hydraulic variable diameter casing shaping technology, it has applied for patent protection in many countries.
