Structural design and material selection optimization for high pressure manifolds near the wellhead

Abstract:

In order to study and improve the impact of fluid/solid erosion on the high-pressure manifold system in oil and gas drilling， according to the conventional manifold layout near the wellhead， this paper establishes the models for three angle elbows of 0°， 45° and 90°， and carries out numerical simulation of the internal flow field of the fracturing elbow according to the basic theory of computational fluid mechanics and with regard to the actual working conditions. Finally， the manifold layout structures for 0° and 45° fracturing installation angles are designed. According to the installation angles of the three elbows and the selection of the three elbow materials， the indoor erosion test was carried out， and the following conclusions were obtained： （1）At different installation angles， the greater the velocity of the fluid outlet with the increase of the number of strokes， the greater the velocity fluctuation of the bend position at any installation angle； if the velocity fluctuation is too large， the bend position will be seriously eroded； （2）The high-speed fluid erosion area is mainly distributed at the inlet of the pipeline near the wellhead fracturing head. In the case of two dislocations， the overall fluid velocity of the manifold gradually decreases from the outlet to the inlet； （3）The erosion area is mainly distributed near the inlet of the pipeline near the fracturing head. There are high erosion velocities at the five outlets of the fracturing head， and the velocity and pressure show a stepwise changewith a stable period in the middle and small pressure at the position with high velocity. At the installation angle of 0° and 45°， the impact velocity of the fluid will be small； （4）42CrMo has strong erosion resistance， and the selection of 42CrMo as the pipeline material will help to prolong the service life of the pipeline.

Key words:high pressure manifold;installation angles of elbows;erosion test;oil and gas drilling