垂直裂缝井椭圆流模型近似解的进一步研究

对垂直裂缝椭圆流模型近似解的研究,发现其计算结果与Cinco-Ley提供的计算结果相差较大.研究结果表明,近似解中加权因子W是无量纲导流系数F_CD等参数的函数,文中给出了无量纲井储系数C_WD=0、裂缝表皮系数S_f=0时的W与F_CD的关系曲线.将新计算出的理论压力值与Cinco-Ley提供的计算结果进行了对比,证明当F_CD≥1时,其计算结果与Cinco-Ley的结果一致.讨论了F_CD<1时该解不合理的原因,并提出了改进公式.两个实例分析结果表明,修正后的解不仅保持了原解计算快的特点,而且计算结果可靠.椭圆流模型近似解已实用化.本文仅就均匀介质地层的椭圆流模型近似解进行了研究,该方法完全可以用于双重孔隙介质地层椭圆流模型近似解的修正中去.

FURTHER STUDY ON THE APPROXIMATE SOLUTIONS OF THE ELLIPTICAL FLOW MODEL FOR WELLS WITH VERTICAL FRACTURES

The approximate solutions of the elliptical flow model for wells with vertical fractures with a finite conductivity are further studied.It is found that there is a greater difference between the calculations given in this paper and the Cinco－ley's calculations.It is made clear that the weighting factor W is the function of the dimensionless fracture conductivity coefficient F_CD and other parameters.The relation curve for F_CD and W with the dimensionless wellbore storage coefficient,C_WD=0,and the fracture skin factor,S_f=0,is presented.The computation dimensionless pressure is compared with the results presented by Cinco－ley.It is concluded that the calculations much approach to the Cinco－ley's ones when F_CD>=1,and the calculations are incorrect when F_CD<1.The improved formula are proposed finally.Analyses of two examples show that the modified solutions not only keep the advantages of high speed of calculation as the old solutions,but the computation results are reliable.The approximate solutions of the elliptical flow model are practical.Although the approximate solutions of the elliptical flow model for the homogeneous reservoirs are studied,the study method can be of good use for the modification of the approximate solutions of the elliptical flow model in the dual porosity reservoirs.