Optimization Of Infill Wellbore Trajectory In Dense Well And Analysis Of Anti-collision Risk

Artificial island is an efficient development mode for producing marine oil on land.With the development of oilfield,the available space of artificial islands is close to saturation,the available space on the ground and wellheads are very limited,and the completion of densely drilled well sections has become a barrier to infill wells.In order to meet the production needs,the infill well trajectory design must be performed on the dense well.When designing infill wells,we must not only meet the targets in the wellbore,but also avoid unintended wellbore collisions.This paper conducts research from the aspects of wellbore optimization model establishment,dense well trajectory optimization design theory,intelligent algorithm trajectory solution method,infill well anti-collision risk assessment model,and system software development.Firstly,investigate the basic principles of several commonly used wellbore trajectory design methods and survey calculation methods,compare and analyze the application range of various methods,select the most widely used inclined surface arc design method,take the target as objective function,take the engineering restrictions as constraint conditions,a commonly used nonlinear constraint model for wellbore trajectory optimization design was established.Complete wellbore track optimization design under dense well by 3D mesh division and ant colony algorithm.Secondly,the calculation model of Brooks collision probability is improved,and a new method for calculating the collision risk of dense cluster well is proposed.This method shows that nominal spacing,radius and the number of reference well will affect interaction probability.Migration probability is determined by the ratio of the arc length of the reference well and the comparison well diameter to the circumferential circumference of the nominal spacing,and uses Brooks method to calculate the collision probability.The actual collision probability is the product of the migration probability and the collision probability.Comprehensive collision probability is determined by the actual crossover probability of the reference well and each comparison well,which is divided into three risk levels according to industry standards.A collision risk evaluation method that takes the multiple well relationship into consideration and uses the comprehensive collision risk as an evaluation index is obtained.Finally,using object-oriented C#programming language,developed infill wellbore trajectory optimization design software system in dense well,input engineering constraints,a optimal trajectory will be designed out which meet engineering constraints and anti-safety requirements.The work in this paper provides ideas for the realization of computer-aided optimization design,which is of great significance for improving the efficiency of field design and construction in oil fields.