Research On Efficient Installation Of Deep-Water Surface Conductor Based On Injection Parameter Optimization

The shallow deep water has the geological characteristics of soft soil and easy leakage.The conventional drilling method has the risks of low cementing quality and easy wellhead instability due to low temperature.The injection method can effectively solve these problems,and has the advantages of no cementing and saving operation time.In this paper,the optimization of injection parameters is studied in the process of injection installation of surface conductor,which provides theoretical basis for efficient installation of surface conductor in deep water.Based on the water jet theory,the damage effect of water jet on soil is analyzed,and the drilling fluid displacement is optimized to meet the rock-carrying and soil-breaking capabilities.The influence of the ratio,the correction model of bit stick-out is established.According to the theory of conductor-soil interaction,the finite element model of the interaction between the conductor and the soil is established,the influence of the jetting parameters on the stress and displacement of the soil is simulated,the accurate characterization of the damage effect of the water jet on the soil is realized,and the influence of the water jet on the soil is preliminarily clarified.Spray parameters and rules for efficient installation of surface conductor.Based on the similarity principle,a simulation test of surface conductor injection installation was carried out,the influence of injection parameters on the installation efficiency of surface conductor in actual construction was clarified,and an optimization model of injection parameters for efficient installation of surface conductor was established.The research shows that the displacement and the bit stick-out have a more obvious effect on the installation efficiency of the surface conductor.With the increase of the displacement,the running speed of the conductor gradually increases,and the bearing capacity gradually decreases.When the displacement reaches 1.18 times of the minimum soil breaking displacement,the running speed of the conductor and the bearing capacity change the most.At this time,the displacement is the preferred upper limit of the displacement,and the minimum earth-breaking displacement is the preferred lower limit of the displacement.With the increase of WOB,the running speed of the conduit first increases and then decreases,which is a quadratic function,and decreases approximately linearly with the increase of the size ratio of the conductor-bit.The bit stick-out has a greater impact on the high-strength formation.In the high-strength formation,with the increase of the bit stick-out,the running speed of the conductor first increases rapidly and then decreases slowly,showing a cubic function relationship.Under these conditions,there is an optimal value for the bit stick-out;in low-strength formations,the bit stick-out increases,and the running speed of the conductor increases slowly.Taking a deep-water well in the South China Sea as an example,the field application of the jetting parameter optimization model for efficient installation of deep-water surface conductor established in this paper is carried out.The application results show that after the injection parameters are optimized,the displacement is 600L/min～4595L/min,the optimal bit stick-out is149.8mm,the injection speed is increased by 18.94%,and the injection time is saved by18.18% with a certain guiding significance.