Anti-Gas Channeling Technology with Gas-Block Plug for High Temperature and High Pressure Wells in the Periphery of the Tahe Oilfield
Excessive gas channeling velocity is a big challenge in the Ordovician high-temperature and high-pressure(HTHP)reservoirs along the periphery of the Tahe Oilfield, Xinjiang. To solve this problem, an analysis was conducted on the mechanisms and influencing factors of oil/gas migration. The study concluded that the main factors affecting the oil/gas migration were the gel strength and the surface tension of fluids in the wellbore. Hence, researchers developed an anti-gas channeling technology with gas-block plug. In this process, researchers selected key treatment agents for gas blocking, such as high temperature rheological modifier SMRM, surface tension modifier SMSM and high temperature fluid loss additive SMPFL. Thus it was possible to match high temperature resistant gas-block plug regimes and processes. The gas-block plug is resistant temperature as high as 200℃, while the surface tension was lower than 22 mN/m. When the gel strength was higher than 30 Pa at high temperature, there was a good level of compatibility with the mud in the wellbore. The anti-gas channeling technology were applied in 5 wells with severe gas invasion in periphery of the Tahe Oilfield. The techniques were then respectively matched with the operations like drilling, logging, coring and completion. The application results showed that the gas channeling velocity was reduced by more than 75%, the safety operation period was extended, and the drilling safety and efficiency were improved. The successful development and application of high temperature resistant gas-block plug could provide a safe and effective well control measure for the drilling and completion of gas invasion HTHP reservoirs.
AAPG Datapages/Search and Discovery Article #130004© Petroleum Drilling Techniques, Issue 5, 2018