Cementation of long open hole in Shunbei block, Tarim Basin

The Shunbei block in the Tarim Basin has complicated geologic conditions, and reservoirs are deep buried, usually over 7 500 m. Pyrolith in Permian leaks seriously. The Silurian formation has a poor pressure resistivity. The Upper Ordovician develops diabase intrusion body, and has a strong collapse stress. To optimize well structure, we used 193.7 mm casing down to the top of intrusion body, facing some difficulties such as deep setting depth (7 000 m) and cementing leakage. We improved cementing slurry column structure and centralizer design, added temperature-sensitive memory plugging material into light-weight cement slurry, optimized leakproof cementing technology, and injected light-weight cement slurry from well hole. In this way, the cementation of long open hole was optimized. This technique was applied and proved effective in 5 wells by two-stage cementation in Shunbei block.