小井眼环空压耗模式的建立及其在吉林油田的应用

小井眼环空压耗计算与常规井不同。文中通过对大量试验数据分析,回归得到了钻柱旋转和偏心弯曲对小井眼环空压耗影响的经验模式,并在常规井压耗模式基础上建立了小井眼环空压耗模式。给出了小井眼中由轴向流动雷诺数和旋转泰勒数共同判别钻井液流态的经验表达式。编制了小井眼水力参数优化和钻井液流变参数优选的程序。计算结果表明小井眼中的环空压力损失与钻柱内压力损失的比值高达25%~30%。利用吉林油田庙1-40井的数据,对理论模式及室内试验结果进行了现场验证。验证结果表明,利用文中建立的小井眼压力损失模型去预测现场小井眼中的压力降,相对误差在6%以内,证明所建立的压耗模型完全可以满足工程施工的需要。对该油田庙5-40井水力参数进行了预测计算,计算结果同样表明了模式的准确性。

MODEL OF ANNULAR PRESSURE LOSS FOR SLIMHOLE AND ITS APPLICA TION IN JILIN OILFIELD

The calculation of annular pressure loss for slimhole is different from that of conventional well. Based on sufficient test data analysis and by regression, this paper establishes the empirical model of slimhole annular pressure loss affected by rotary drill string and eccentric buckling. The model of annular pressure loss for slimhole is established on the basis of the model for conventional well. The empirical equation of distinguishing drilling fluid state by Reynolds number in axial flow and Tyler number of rotation is also presented. Hydraulics optimization and drilling rheological parameter optimization are programmed. Calculations indicate that the ratio of the annular pressure loss and drilling string internal pressure loss is upto 25%~30%. Based on the data from the well Miao 1-40 in Jinn Oilfield, the theoretical model and lab test data are field verified. Field verification indicates that the relative error of pressure loss in the slim hole is less than 6%, when the pressure loss is predicted by the model established. Thus, the model is proven to meet fully the needs of engineering operation. The hydraulics of well Miao 5-40 in the oilfield is predicted. The accuracy of the model is also indicated by the prediction.