Tectonic stress is a nature phenomenal and it naturally occurs due to lateral force from the formation. Typically, if the rig is close to mountains, there is high chance to face with the tectonic stress issue.
The later force will create stress which will squeeze sandstone causing under gauge hole. Moreover, the lateral stress will fracture shale and create additional cuttings.
The basic system means the drill string consisting of drill pipe, drill collar and a bit (no downhole tools). The process for drilling hydraulic optimization is simple. The following steps demonstrate how to optimize drilling hydraulics for the basic system.
• Select drill pipe and drill collar which provide pressure loss at a minimum for the range of depth and flow rate.
• Decide the methods to optimize drilling hydraulics. If you drill a shallow hole section, the maximum impact force is recommended. However, if you drill a deeper section, the maximum hydraulic horsepower is better than the maximum impact force.
• Determine flow rate to meet your optimization requirement at the end of the bit run. The curve below gives you a idea how you can get the flow rate from the char at each particular optimization method.
This is my last post of this year 2011. First of all, we would like to thank you everyone who read this blog and we enjoy sharing oilfield knowledge very much. During this year 2011, we posted several articles in many aspects of drilling as drilling formulas, well control, drilling operation, oilfield book review, etc. However, we still have a problem with our web hosting from time to time and we just order a new virtual private sever. Hopefully, the technical problem like this will not be happened in the future.
As you might not know, we have three websites regarding oilfield.
Drilling Formulas – https://www.drillingformulas.com
Drilling Mud – http://www.drilling-mud.org/
Petroleum Engineering Information – http://www.petroleum-engineering.net/
What will we do for the next year 2012?
We have been discussing about our goal for next year and this is what will be happening.
• Well control articles – well control equipment (BOP), complication, well control technique (lubricate and bleed, volumetric, etc)
• Drilling hydraulics articles
• Additional drilling formulas and sample calculations
• Application of drilling formulas spread sheet – we will show the example on how to use the drilling formulas spread sheet into real drilling operation.
• Oil field dictionary – we are working on it now and we should have this website done in few weeks. This part we need your input to help grow the oil field wording too because only our team may not be able to collect all the meaning.
• Free oil field dictionary program
• Free stuck pipe e-book
• Free petroleum engineering schools hand book
• Drilling waste management
• Drilling operation useful tips
• Useful oilfield spread sheet
• Oilfield book review
• Additional petroleum engineering schools
Please feel free to give us feedback or suggestions in any aspects so we can use it to improve our website.
Wish you have good heath, wealthy and all best with you. See you next year 2012.
Typically, drilling hydraulics optimizations (maximum jet impact and maximum hydraulic horsepower) are based on an assumption of a fixed system. In real operation, you cannot fix flow rate to drill all the way to TD because the system pressure loss is changed because of hole depth, drilling mud properties, wellbore conditions, etc.
There are two ways of optimizing drilling hydraulics which are optimization at the beginning of the run and at the end of the run.
Drilling Hydraulics Optimized at the Beginning of the Run
If the system is designed to meet the maximum hydraulic horsepower at the beginning of the well and the pump pressure is maintained constant at the designed value, when the well is getting deeper, the flow rate must be reduced to maintain the pressure. With this situation, it will cause the jet velocity and hydraulic horsepower dropping (see the curve below) at the end.
The design of hydraulic optimization begins with downhole component and an analysis of pressure losses as a function of flow rate.
Before I will explain you about the pressure and flow rate curve, I would like to get the following term across. The surface pressure (pump pressure) is equal to the system pressure loss and the pressure loss across the bit.
P surface = P system + P bit
The curve below demonstrates a system pressure loss curve and a pressure loss across the bit as Y-axis and a flow rate as X-axis. The system pressure loss curve starts at the maximum surface pressure and is drawn invert with the bit pressure loss curve (see the curve below more understanding).
