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Study on the recycling of fuzzy ball bionic drilling fluid

Chen Yang, Lihui Zheng, Jie Zhang, Zhiguo Wei

A novel bionic drilling fluid imitating fuzzy bacteriaÂÂ’s cell structure was introduced in the present paper, which was named fuzzy ball drilling fluid. The special structure of “one core, two layers, three membranes” makes fuzzy ball bionic drilling fluid have a automatic plugging ability and be able to resist high pressure. The composition of the fuzzy ball bionic drilling fluid can be adjusted according to different formation conditions. The main ingredient of the fuzzy ball bionic drilling fluid is vegetable gelatin and cellulose, so it is atoxic and environmentally safe. The fuzzy ball bionic drilling fluid has been applied successfully in more than 20 wells in China. Three methods were proposed in this paper to recycle dumped fuzzy ball bionic drilling fluid, which are 1) separating by flocculation and produce low-density cement slurry; 2) separating by gel-breaking and discharge directly; 3)curing directly and produce solid cement. The lab experiments were conducted to study the feasibility of each method. The results show that 1) the cement slurry produced by flocculation separating liquid can satisfy the demand of shallowcementing of wells; 2) the separating liquid by gel-breaking satisfies the secondary standard of “GB8978-96 National Sewage Discharge Standard”; 3) the strength of solid cement produced by curing the dumped fuzzy ball bionic drilling fluid is high enough to be used for further well stimulation, and the leach liquid satisfies the secondary standard of “GB8978-96 National Sewage Discharge Standard”. All the three recycling methods can be adopted according to different working conditions. The research results improved the technical specification of the fuzzy ball bionic drilling fluid and proved a train of thought to recycling the dumped drilling fluid.