Abstract
With high oil demand and prices, and production of most conventional-oil reservoirs in decline, industry focus in many parts of the world is shifting to exploitation of heavy oil, extra-heavy oil and bitumen. Hydraulic fracturing stimulation is also an important technology for some tight heavy oil formations with low porosity and ultra-low permeability in the Songliao and Bo haiwan basin in North China, while application of conventional fracturing technology in the recovery processes of heavy oil reservoir will meet some problems such as high viscosities, poor flow properties and high densities in compared to conventional oil. This paper describes a successful case of proppant fracturing on an ultra-low peameablity and high viscosity (17.6API) sandstone heavy oil reservoir in eastern China. Several technologies including pre-pad fluids, hydraulic fractures numerical simulation for enhancing heavy oil drainage area, tip screen-out (TSO) fracturing in order to improve fracture conductivity, multi-step slurry injection schedule, low damage gel were used.
More than 33 treatments with new technologies in Huabei, Liaohe oil field have been performed with encouraging results, 88.5% efficiency with accumulated incremental oil of 213,050 ton and the average post-fracturing rate reach to 25.9m3/d satisfied as expected, which is three times of before stimulation, while in the past, there were many treatment failures. It has a great significance not only in improving fracturing treatment effect in above mentioned heavy oil formations but also in perfecting low damage fracturing technique as well.
