Drilling fluids circulation system for well drilling
Drilling fluids circulation system must hold sufficient space to process drilling fluids in suction line or the upstream prior to balance pipeline. This will make fluids full of well bore when drill starts.
The drilling fluids system on ground should including 3 sections. The suction part, configuration part, cleaning part.
Suction and test section
Actually, suction and test section is the final part of circulation system. Almost space can be used to analyze and evaluate drilling fluids. Recirculation and reuse is the priority when we maintain clean drilling fluid. At this section, drilling fluid should be mixed, adjusted and agitated throughly. Before drilling fluid entering well head please leave sufficient time for changing it property per drilling condition. Prevent any swirl or air entering drilling fluids.
To avoid drilling pump sucking air, suction tank should be mounted a vertical plate to cut off swirl may occur under agitator running. If the liquid level is relatively low in suction tank there must be other way to prevent swirl, such as put a flat bas plate over suction line to cut down the swirl.
A proper mud agitator is important. Thus we can get the even mixture of drilling fluid in suction pool and well bore. Please refer to our previous post on mud agitator operation and configurations
Configuration / compounding part
All the useful solids control chemical additives are fed into mud tank at upstream part prior to suction and test section. The drilling fluid compounded at site should be added into system via this mud tank. All drilling mud come from others should be fed into system after solids removal by shale shaker.
Drilling mud gun can be used in configuration and suction&test section for more even mixture.
Cleaning section in drilling fluids circulation
Prior to new processing materials feeding into drilling fluids the unnecessary drilling cuttings and gas should be got rid of. As cuttings will decrease drilling fluid property and lead related cost increase. Too much drilling cuttings will cause drilling blocked and bad well cementing
Every well and every different type of drilling fluid hold different limit. Each solids control equipment is designed for filtering certain size range particle. These equipment should be installed obey certain order. According to separation point the equipment can achieve, from coarse particle to finer and finer particle.
Usually, the shale shaker
will get rid of 74~440 microns solids. And screens are from 40 mesh to 200 mesh. Then, hydrocyclones get rid of particles larger than 15 microns. For unweighted drilling fluids, we use decanter centrifuge to get rid of solids larger than 5 microns.
Please refer to our previous articles for better understanding this text. Or you are welcome to visit Aipu solids control blog for more details on solids control.