The Research Of Horizontal Multilateral Well Optimal Design

The application of horizontal multilateral well technology can increase therange of oil and gas drainage, reduce drawdown pressure, and then increase oiland gas production and lower the development costs. This technology hasalready being used in low percolation reservoir at home and abroad. Based onensuring drilling engineering safety and costs control, the optimal design ofhorizontal multilateral well is also a vital part of the efficient development of oiland gas. The combination of this optimal design with practical drillingengineering and development optimization theory plays an important role inimproving the overall benefits of oil field’s development.This author in this paper gives a systematic literature review on theapplicability principle of reservoir in horizontal multilateral well path design,and at the same time, he selectively studies the current drilling and completiondesign. Combining with the conventional design methods of two andthree-dimension well trajectory, the author analyzes the three-dimension design method in horizontal multilateral well by using spatial arc. This paperemphatically analyzes the productivity prediction model (especially by usingsemi-analytical method) of horizontal wells and multilateral wells. Throughcalculating productivity of branched wells, and taking the example ofherringbone well, this paper analyzes the morphological changes of horizontalmultilateral well. According to the productivity prediction model, the authorconducts an optimal analysis on symmetry, branch locality and branchmorphological parameters (branch angle, branch quantity, and branch length) ofthe herringbone well; meanwhile, by carrying out orthogonal experiments onbranch morphological parameters, the author also analyzes some importantfactors affecting productivity of oil wells. At last, combined with the example ofherringbone well, this paper conducts a comparative analysis.