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He C.,Langfang Branch Institute of RIPED
Drilling Fluid and Completion Fluid | Year: 2015

Acidification fluid formulation and acidification technology are studied for the best results in the acidification of thick highly inhomogeneous sandstones. It is concluded that for reservoir formations with high shale content and that are poorly cemented, the concentration of the prepad acids shall be reasonably higher (for instance, the concentration of HCl shall be increased to 15%), and the main acid (for acidification) HF shall have its concentration reduced to, for instance, 1%. Slabbed cores in combination with SEM can be used to determine the damaging depths, providing clues for the amount of acids to be used in acidification. For thick porous reservoirs, a combination of packer, perforation with variable intensities and diverting acids can be used in reservoir reformation. For reservoir formations with developed fractures, high flowrate, large amount of fluid and high pump pressure together can be used in eliminating deep plugging of the reservoir. ©, 2014, North China Petroleum Administration Drilling Technology Research Institute. All right reserved.


Wang H.,Langfang Branch Institute of RIPED | Qiu X.,Langfang Branch Institute of RIPED | Zhai W.,Langfang Branch Institute of RIPED
Drilling Fluid and Completion Fluid | Year: 2015

Six types of drag reducers were studied for their solution viscosities and drag reducing effects at different concentrations and in pipeline flow. The study shows that the water solutions of these drag reducers have power law flow patterns, and the drag reducing ratios increases with the increase of the concentrations of these drag reducers, if the concentrations are in certain ranges. Viscosity of the solution and ion characteristics have no obvious effect on the drag reducing ratios of these drag reducers. At the same concentrations, drag reducers having molecular weight (MW) greater than 1000000 have almost the same drag reducing ratios. The main factor affecting the drag reducing performance is the molecular structures of the reducers. Drag reducers with low MW and long molecular chains, those with branched and long molecular chains, and those with flexible, helical molecular structures have drag reducing performances that are much more stable. Long chain drag reducers with branched chains dissolve quickly in water and have good drag reducing performance in a wide range of Reynolds numbers. Drag reducers with low MW are easy to degrade and hence impose very slight damage to the reservoirs. These drag reducers are suitable for use in large scale shale reservoir fracturing with slippery water fracturing fluids. ©, 2014, North China Petroleum Administration Drilling Technology Research Institute. All right reserved.

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