Drilling and completion technology for 5-multilateral sulfur-bearing gas wells with high temperature and high pressure in Sichuan Basin

Well MX023-H1 is a 5-multilateral well in the gas reservoir in Longwangmiao formation, Sichuan Basin, and the purpose of drilling this well is to verify the adaptability of multilateral well technology in the efficient development of deep carbonate gas reservoirs. As the first level five multilateral sulfur-bearing gas well with high temperature and high pressure in China, the drilling and completion operation of the multilateral borehole is facing with many technical difficulties, such as high completion level, superabundant operation procedures, strict wellbore quality requirements, difficulty in running complex casing strings, and high-performance requirements for cementing sheath to prevent gas channeling. For this reason, in order to ensure the stability of the connection between the multilateral wellbore and the main wellbore during the later production period, the measures such as increasing the window strength and selecting stable formation windows were taken. Designing smooth borehole trajectory and improving the anti-slump performance of drilling fluid can ensure an inerratic well diameter and reduce the difficulty in running casing. By using the new designed Ø177.8 mm curved casing, the drafting operation of Ø215.9 mm multilateral borehole with a length of nearly 5 000 m has been completed, meeting the re-entry and drafting requirements for multilateral borehole, and creating good wellbore conditions for the smooth running of multilateral casing. The gap of the opening groove at the front end of the wall hook of the wall-mounted hanger was increased from 21.66 mm to 25.66 mm, which improves the success rate of wall-hanging. The three-set cement slurry system combined with the pressure-controlled balance cementing technology ensures the cementing quality under the condition of coexistence of overflow and leakage in the multilateral wellbore, with the qualified rate of the first interface reaching 97.6%, and the qualified rate of the second interface reaching 100%. Field application shows that the supporting technology can meet the drilling and completion requirements for the 5-multilateral sulfur-bearing deep gas wells with high temperature and high pressure, and the successful implementation of the drilling and completion operation for this multilateral well can provide reference for the subsequent popularization and application of 5-multilateral well technology.