火成岩研磨性试验研究

Experimental Study on Igneous Rock Abrasiveness

  • 摘要: 火成岩钻井设计优化的关键是了解火成岩的可钻性和研磨性,但至今还未形成一套测试火成岩研磨性的有效方法。为此,采用自主研发的岩石研磨性测定装置,测试了不同岩性火成岩岩样的研磨性,并分析了火成岩研磨性与其单轴抗压强度和矿物成分含量之间的关系。测试结果表明,在岩样转速8 r/min、钻压800 N、钻头转速198 r/min的条件下,以破碎单位体积岩石研磨标准件的磨损质量作为研磨性指标,可以很好地分辨不同岩性火成岩的研磨性,且火成岩的研磨性与其单轴抗压强度和等效石英含量均呈较好的幂函数关系。研究结果表明,以火成岩单轴抗压强度为基础建立的火成岩研磨性预测模型,可以很好地预测火成岩的研磨性,可为优化火成岩钻井设计提供理论依据。

     

    Abstract: Igneous oil and gas reservoirs are hot spots in well drilling. But, drilling them is extremely difficult due to the highly abrasive nature of the rocks. So, drillability and abrasiveness of igneous rocks must form the basis of drilling optimizition design. The problem is, however, that igneous rock abrasiveness testing methods have not yet been formulated. So, in this paper, we describe the development of a rock abrasiveness measuring device used to test the abrasiveness of igneous rock samples with different lithologies. We also examined the relationship between the abrasiveness and their uniaxial compressive strength of igneous rocks, and mineral content. We found that under the conditions of rock sample rotary speed of 8 r/min, WOB of 800 N, and drill bit rotary speed of 198 r/min, the weight loss of grinding standard part of per unit volume broken rock within a certain time can be used as abrasiveness index to distinguish the abrasiveness of igneous rocks with different lithologies. The abrasiveness of igneous rocks shows a good power function relationship between uniaxial compressive strength and equivalent quartz content. The research results show that the abrasiveness prediction model based on the uniaxial compressive strength of igneous rock can predict the igneous rock abrasiveness very well and provide a theoretical basis for optimizing the drilling design for wells in igneous reservoirs.

     

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