摘要
在水平分支井钻进过程中,地质导向技术是保证井眼顺利进入油层,并在油层中穿行一定距离的重要技术。结合渤海海域渤中25-1油田曲流河相沉积地层水平分支井开发实例,介绍了Powerdrive和GST等地质导向钻井工具,并进一步结合LWD/MWD和综合录井技术,探讨了复杂地层的地质导向技术,包括:依据近钻头电阻率、自然伽马判断钻头处的岩性;依据衰减电阻率和相位电阻率的差别判断钻头是否接近泥岩;利用顶密度和底密度的差别判断泥岩位置;利用顶底密度差别计算地层倾角;利用电阻率曲线的极化角现象识别地层界面;依据钻时和气体数据,结合岩屑、扭矩和D指数判断钻头处岩性;利用地层的韵律性,结合砂岩粒度变化判断井眼位于油层中的位置等。综合利用这些技术,可以在现场及时指导钻进方向,保证井眼轨迹尽可能多的位于油层中。从应用该技术钻进的7口水平井及水平分支井效果上看,钻遇油层率为95.3%,达到了非常理想的水平。导向工具的先进性、导向技术的全面性及技术人员的素质水平,是保障水平井导向最优化的前提条件。
During drilling of the horizontal branching wells, the geologic steering technique is an important technique that guarantees wellbore to enter into oil layers smoothly and pass a certain distance through oil layers. Dealing with the horizontal branching wells development samples of meandering stream facies sedimentary formation from Bozhong 25-1 oilfield of Bohai, the paper introduced the Powerdrive, GST and the other geologic steering drilling tools, and through further combining with LWD/MWD and the comprehensive mud logging techniques, probed into geologic steering technique for complex formations, which included identification for near-bit formation lithology with the near-drilling bit resistivity and natural gamma, identification for bit being near mudstone or not with the differences between attenuation resistivity and phasic resistivity, identification for mudstone position with the density and bottom density differences, formation dip calculation with the top and bottom density differences, identification for bed boundary with the polarization angle phenomenon of the resistivity curve, identification for formation lithology near the bit with drilling time, gas data, cuttings, torque and d exponent, identification for borehole position in the oil layers with the formation rhythmic nature combined with the variation of the sandstone grain size. Comprehensively utilizing the above techniques, the drilling direction could be guided promptly at wellsite to guarantee the well track to lie in the oil layers as much as possible. Seen from the results of seven horizontal wells and horizontal branching wells which were drilled with these techniques, the rate of the oil layers drilled and met was 95.3 percent, which came up to the ideal level. The advantage of the steering tools, the complete set of the steering techniques and the technical level of the personnel was the prerequisite for ensuring the steering optimization of horizontal wells.
出处
《录井工程》
2006年第3期1-5,共5页
Mud Logging Engineering
