The Trajectory Optimization Design And Application For Shallow Extended Reach And Stepped Horizontal Well In Jilin Oilfield

In recent years, shallow horizontal well technique is widely and successfully applied in Jilin Oilfield. This has made many shallow reservoirs possible to be developed whose buried depths are between 190m and 600m, and made contributions to keep the producing capability stable and increased in Fuyu old region and to the whole Jilin Oilfield. Nevertheless, as the increase of horizontal well displacement and the operation of stepped trajectory, the friction resistance increases greatly during drilling and casing operation, so that the navigation drilling and casing operation is difficult and even the casing cannot reach the designed depth. Therefore, how to appropriately design the well trajectory to overcome the big friction resistance during drilling and casing operation has become the key technique that needs solving in the shallow stepped horizontal well drilling.The shallow extended reach and stepped horizontal wells in Jilin Oilfield have a characteristic of shallow vertical depth, long horizontal section, big whole well horizontal displacement, big friction resistance during drilling and casing operation and so on. Based on the common used model for friction resistance and torque calculation, through adding a rigid force on the string to cause friction resistance, the author builds up a model that is suitable for the friction resistance and torque analysis of extended reach and stepped horizontal well, and a method to analyze the throughput capacity of drilling and casing string. Using the model and the method, the analysis of friction resistance during drilling and casing operation as well as the throughput capacity of drilling and casing string under different trajectories can be accomplished. Moreover, considering the conditions that one stepped horizontal well has more than one target, and the step section trajectory design becomes more complicated along with the increase of targets, according to the different correlation and combination among the targets, 5 basic models on step section trajectory design have been established, and the resolution and design methods have also been given. Using these 5 models, step section trajectory design for any complicated multi-target stepped horizontal well can be easily accomplished.Based on theoretical research, considering the common requirements and characteristics for shallow stepped horizontal well design in Jilin oilfield, the author makes the optimization design analysis and friction resistance influential factor analysis for step section trajectory of shallow stepped horizontal well. The design principle, procedure, model and method have been given, and a technique on step section trajectory design for stepped horizontal well has been established. These techniques can satisfy the need of optimization design for step section trajectory, and can obtain the optimum trajectory that has the slightest friction resistance when using the same drilling or completion string, which has provided technical support for shallow stepped horizontal well design in Jilin Oilfield. Besides, a wellhead pressure device is developed and has a good effect on field.Through field application on 11 horizontal wells whose horizontal displacement and vertical depth ratio is more than 1.8, a drilling support technique on shallow extended reach and stepped horizontal well drilling which is suitable to the shallow reservoir development of Jilin Oilfield has been established, and has been successfully applied in the oilfield.