Research On Thin Barrier Fracturing Technology Of C4-5 Layer In Chunhua Oilfield

The main Chun1-3 formation of Chunhua olifield enters the high water-cut stage.So it needs to develop Chun4-5 formation in the lower part of Chun1-3 by fracturing to maintain continuous and stable production.In this paper,for the problem of fracture failure due to the conventional fracture height prone to breakthough barrier,the stress profile was established relying on calculation of reservoir stress,to obtain press difference between Chun 3 formation and Chun 4 formation;The fracture height is controlled in the chun 4-5 formation by optimizing parameters such as pump rate and volume of sand.The VES hydrofrac fluid is selected for it’s good sandcarrying capacity,easy discharge and low injury by the experiment of sandcarrying capacity and filter loss.The cracks are evenly paved by the simulation optimization of the percentage of prepad fluid and the ratio of the average sand liquid,to obtain reasonable fracture conductivity and ensure the fracturing effect.By improving fracturing string instruments of packer,hydraulic anchor,sandblasting machine structure,the problem of sand sticking is avoided since the Y221+K344 packer with the function of anti-flushing and preventing sand sticking.The research results show that the press diffience of formations of Chunhua oildfield is between0.1 to 3.7MPa,but most of them is less than 3MPa,and the barriers height is about 1.6 to 12m,the formation press has a little diffence.So it’s difficult to control fracture height.But the risk of operation is effectively reduced by optimizing pump rate of 2.5-3.5m~3/min、volume of sand1.8-2.5m~3/m.