支撑剂充填层非达西流试验研究

EXPERIMENTAL STUDY OF NON-DARCY FLOW FOR PROPPANT-FILLING BEDS

在生产过程中 ,油气在裂缝中绝大多数处在非达西条件下流动 ,这对压裂设计及产能预测非常重要 ,通常用Forchheimer方程描述。 2 0 /4 0 (0 .4 5～ 0 .90mm)支撑剂充填层非达西流实验结果表明 ,在低流速条件下偏离Forchheimer方程 ,在高流速下Forchheimer方程线性很明显 ;紊流系数和渗透率与支撑剂粒度、球度、圆度、支撑剂充填层孔隙度和实验条件等有关。在非达西流条件下 ,模拟压裂液对支撑剂充填层损害及返排实验表明 ,压裂液对非达西流的紊流系数和充填层渗透率均有一定影响 ,甚至会造成渗透率长久性的损害。实验还表明 ,支撑剂充填层非达西渗流的研究 ,有助于优化压裂设计和提高压后产能预测 ,非达西渗流紊流系数和渗透率可作为评价和筛选支撑剂性能的重要指标。

It is very important for the fracturing de sign and productivity forecast to understand oil and gas flow in fractures mostly under non-Darncy conditions during pro ducing process. This situation is described with Forchheimer equation. The experimental results of non-Darcy flow in the 20/40(0. 45-0.90 mm) proppant-filling bed show the test data deviate from Forchheimer equation at low flow rate, and the Forchheimer equation appears obvious linearity at high flow rate. The turbulence coefficient and permeability is re lated with the grain size, sphericity and roughness of the proppant, and the porosity of the proppant-filling bed, and the experimental conditions. The damage to proppant-filling beds and flow-back of fracturing fluid is simulated under non-Darcy flow conditions. The tests show fracturing fluid will influence the turbulence coefficient of non-Darcy flow and the permeability of the proppant-filling beds, even cause permanent damage to the proppant-filling beds. Also, the tests demonstrate the study of non-Darcy percolation for the proppant-filling beds is useful to optimize fracturing design and improve productivity forecast. And the turbulence coef ficient and permeability of non-Darcy percolation can be re garded as the major indexes to evaluate and select the prop-pant.