Pierre Shale Research Paper

Pierre Shale

Introduction:

Millions of years ago, the earth had a different geographical look and the seas covered vast quantities of land that can now be seen. Many present day coastlines were completely submerged and the waters invaded deep into continents making vast portions of the landmasses an aquatic environment. These aquatic environments supported many different types of living creatures, from large mammals all the way down to plankton, algae, and microscopic organisms like bacteria and such. As time went on and these bodies of water subsided, they left an organic layer that covered the geographic area where it was. This organic matter, overtime, would eventually get covered up and it would form different layers of the earth. Many

They wanted to try to develop a water-based mud that would not have a strong effect on the Pierre shale and would be environmental friendly to dispose of the cuttings. They studied the PDC bits in order to help the drilling rates while drilling through this troublesome shale. They performed the project with two 8 1/2 –in PDC drill bits and nine different types of drilling fluids. Two of the drilling fluids were oil based while seven of the drilling fluids were water based. The different types of drilling fluids can be seen in figure two. The cores used for the experiment came from outcrops of the Pierre shale in Colorado and they were preserved in diesel oil in order to make the shale fully saturated during the experiment and this would model a soft formation where bit balling would be prevalent [5]. The two experimenters also used two types of PDC bits for the experiment; a steel-body ribbed PDC and a matrix-body bladed PDC bit. Hemphill and Clark ran many different tests changing the flow rate, weight on bit, drilling fluids, and the two different drill bits. They first concluded that the two different bits had different penetration rates for the Pierre shale. The matrix bodied bladed bit drilled faster than the steel body bladed bit in all of the mud samples

This is prevalent in many present day drilling operations. Oil based mud can be scientifically altered so well to match the formations being drilled in, that it lessens the likely hood of bit balling or slow penetration rates. They did find that the water-based mud that had the cationic polymer in it, exhibited the highest rate of penetration of all the water-based mud in every tests