Abstract
China Changbei block development is an unconventional tight gas project in China Ordos basin. The main pay zone of Changbei is braided river sedimentation with inconsistency of sandstone. Well stimulation with hydraulic frac was the predominant concept for tight gas development in the basin with low individual well producing rate. Innovative Dual-Lateral horizontal well concept was selected for Changbei block thin gas reservoir development. Each cluster planned 3 Dual-Lateral horizontal wells which could cover a 3 km radius circle drainage area. The Dual-Lateral well spud with 16" hole to about 600m to secure top formation, then continue with 12-1/4" hole section landing in reservoir formation at around 3,400m AHMD (2,900m TVD) and cased off with 9-5/8" casing. Two 8-1/2" lateral legs, with each being turned for around 45 degrees in azimuth to separate from each other, string up as many as sand bodies in designed 2,000m leg length in reservoir section to maximize production. The Dual-Lateral horizontal well design proven to be successful for China Changbei tight gas development.
By 2022, Changbei completed in total 57 Dual-Lateral horizontal wells and maintained productivity over 3.2BCM per year for more than 14 years, played an important role for China gas supply. This paper detailly described the well design and execution of Dual-Lateral horizontal wells including drilling challenges and countermeasures including casing exit and open hole sidetrack practices, hole cleaning, drill pipe and BHA selection, etc. The paper will give a full picture on Dual-Lateral horizontal wells construction.
