Ultra-high-density drilling fluid is crucial to the success of drilling and completion of ultra-deep reservoirs.
Qingdao Millennium Energy Co., Ltd. teamed up with China University of Petroleum(EastChina) systematic evaluation and screening research the weighting agent in high temperature and high pressure conditions,developed ultra-high-density drilling fluid system（2.35-2.65 g/cm3).
During pretreatment screening found that ordinary barite and hematite are not the best weighting agent,because they tended stack in high-density condition,Even at a density of 2.0 g/cm3, the emulsion-breaking voltage(ES) of the system was very low.In contrast, manganese tetroxide, ilmenite, and surface treated barite as weighting agents had acheived better rusult in various performance tests of drilling fluids.When the purity of manganese tetroxide was greater than 95% and the purity of ilmenite was greater than 85% , the ES value is greater than 2000V,it shows stable and effective potential that can be used as a weighting agent in ultra-high density oil-based drilling fluid systems.
The system has been deployed in the Middle East at the Missan Oil field in Iraq，which average well depths are more than 5,000m and maximum well temperature is 180°C
The results show that The upper density limit of the barite drilling aggravation capacity during the process is around 2.65 g / cm3.Thus require ultrapure level API barite and micropulverized barite to maintain the high density(Higher densities and finer particle sizes to keep the system weight and suspended),significantly the cost will increase,and challenge the production technology and capacity.Due to manganese tetroxide and ilmenite have excellent drilling fluid rheological properties will be a potential alternative to barite.Using this complex weighting agent, the ultra-high density drilling fluid system has broad application prospects in more severe geological conditions.
