花古101区块低渗透率含裂缝砂岩储层产能疑难分析

Analysis on Productivity of Low Permeability Fractured Sandstone Reservoir in Huagu 101 Block

花古101区块储层致密、裂缝发育、非均质性强,导致产能预测存在较大误差。从平面径向流模型出发利用摩尔斯分类筛选法对产能敏感因素进行灵敏度分析,再结合各相关参数的变化范围得到其对产能的影响程度排序:渗透率>厚度≥压差>表皮系数>原油黏度>体积系数>供液半径>井眼半径,渗透率影响程度最大,裂缝是控制产能大小的重要因素。直接利用电成像测井资料与间接利用非均质参数实现对裂缝发育的综合定量评价。建立了声波时差和自然伽马分形维数差值与电成像孔隙度谱二维劳伦兹系数的相关性,结果表明分形维数差值越大,二维劳伦兹系数越小,地层非均质程度越强,裂缝越发育。考虑裂缝计算地层总渗透率对产能进行预测,计算结果与试油产能对应较好,实现了对花古储层产能疑难诊断分析。

Reservoirs in Block Huagu 101 are tight, fractured and strongly heterogeneous, so that it is hard to get accurate productivity prediction In this paper, the Morse method is used to analyze the sensitivity of productivity sensitive factors based on a plane radial flow model, and then according to the variation range of each relevant parameter, the sensitive factors are ordered by their influence on productivity, i.e. permeability > thickness ≥ pressure difference > skin factor > oil viscosity > volume coefficient > drainage radius > wellbore radius. Permeability has the greatest impact on productivity, and fracture is an important factor on controlling production. Comprehensive and quantitative evaluation of fracture development is carried out by direct electrical imaging data and indirect heterogeneous parameters. The correlation is established between the fractal dimension difference(between acoustic slowness and natural gamma)and the two-dimensional Lorenz coefficient of electrical imaging porosity spectra. The results show that the greater the fractal dimension difference and the smaller the two-dimensional Laurentz coefficient, the stronger the heterogeneity of formation and the more developed fractures. The productivity predicted by the total permeability by considering fractures is in good agreement with the productivity by production test, indicating the method proposed is effective to evaluate the productivity of Huagu reservoirs.