Abstract: The existence of the optimal horizontal section length of a horizontal well is comfirmed through analying the change of the incomes and expenses of a horizontal well with the prolonging of its horizontal section length. In the optimization model, much attention is paid to the special constraint on horizontal section length and the selection of objective function of the model, without which the optimal horizontal section length can not be worked out smoothly. By analying the relationship between them, the absolute and relative measurements, i. e. NPV & NPV/L, become parts of organic whole and the optimization model is thus set up. It is shown that the horizontal section length will be designed too long to be the optimal length if the special constraint is withdrawn from the model, and furthermore, to the same horizontal well its optimal length is different in the different cases whether vertical wells are drilled together with the horizontal well or not. Qualititively, the optimal length of horizontal wells drilled together with veftical wells are always longer than those of horizontal wells in which case only horizontal wells are drilled.

Key words: horizontal well, horizontal section length, optimization design, net worth of present value, model

摘要： 通过分析一口水平井的投入与产出随水平段长度的延伸而发生的相应变化,证实了水平并最优水平段长度的存在。在建模过程中,着重对模型目标函数的选取及水平段长度的效益约束方程进行分析研究。通过对绝对效益指标NPV及相对效益指标NPV/L间相直关系的分析,首次把二者融为一体,建立了以NTV(L)为目标函数以NPV/L(L)为(其中之一)约束方程的优化模型。通过模型分析及实例印证,可以清楚地看出,如果则除以NPV/L(L)指标为约束条件的效益约束方程,水平段长度就会设计得过长,并且,即使对于同一口水平并在其所在区块内,是否有直井混入,其最优水平段长度值各不相同,定性地,采用水平井与直井混合开发时的最优水平段长度要大于全部采用直井开发时的最优水平段长度值。

关键词: 水平井, 水平井段长度, 优化设计, 净现值, 模型