蒙特卡罗模拟研究水平井密度测井中岩屑层的影响

利用蒙特卡罗方法,分别通过改变地层模型的岩性和水平井筒模型内岩屑层的厚度,研究了在多种地层中,水平井筒内0-5cm厚的岩屑层对密度测量的影响.为了保证模拟结果的可靠性,把模拟结果与前人实验数据进行了基准校正.研究表明,厚度在2cm以内的岩屑层对密度测量的影响是稳定的,可以用脊肋图的方式进行补偿校正,而岩屑层厚度大于2 cm之后,其对密度测量的影响不再容易校正.针对DSDL-8723双源距密度测井仪,初步给出了水平井中岩屑层对孔隙度影响的校正图版和公式.

Monte Carlo simulation on influence of cutting beds on density log in the horizontal wells

Cuttings debris may be deposited in the bottom of a horizontal hole because of gravity of the earth. It has lower density than the formation,so cuttings beds can have a significant effect on the density log responses. Monte Carlo method was used to study the effect of cuttings bed on the computed log density,with various formation densities and cuttings bed thicknesses of 0-5 cm in the horizontal borehole. In order to guarantee the reliability of results,simulation results were compared to the experimental data. MC simulations show that the density measurement can be corrected using the ridge-rib graph,if the thickness of the cutting bed is less than 2cm. Otherwise,it is difficulty to correct the effect of the cutting bed on the formation density measurement Finally,the cuttings beds correction charts and formulas for DSDL-8723 double-detector density logging tool which is in the horizontal borehole are made preliminarily.