Ninety f o u r p o s s i b l e o i l s h a l e s e c t i o n s i n s o u t h e r n I d a h o were l o c a t e d and c h e m i c a l l y a n a l y z e d. S i x t y-t w o o f t h e s e s h a l e s show good promise o f. p o s s i b 1 e o i l and p r o b a b l e g a s p o t e n t i a l .

In recent years the construction of horizontally drilled wells has become commonplace. The horizontal sections of these wells have continued to increase in length as equipment and methods used in constructing these wells have improved. As lateral lengths have increased, so have the challenges associated with drilling and completing these wells. The high TMD/TVD ratios seen in many wells often presents challenges during the installation of casing and liners. The primary issue is the friction associated with horizontal well profiles and the absence of adequate vertical casing weight. In order to combat the problems associated with getting casing/liners to bottom, operators are increasingly using downhole vibratory tools to aid these operations. Vibratory downhole tools primarily help by breaking the static friction between the workstring and wellbore or casing. These tools are commonly used in horizontal well drilling operations but more recently these tools have also begun to be run on casing strings with great success. In this paper, the results of field tests using a downhole vibratory casing tool on a group of wells in the Niobrara and Codell formations are presented. Eight (8) wells were considered during the study. A vibratory casing tool was run in four (4) wells. Casing was run in four (4) additional wells in which no vibratory tool was used. The wells involved in the testing were completed with 4-1/2″ 13.5# P-110 liner in 2-section laterals. Evaluation of the data shows a 121% average increase in running speed while rotating the liner in the hole when using the vibratory casing tool, resulting in an average of a 23 hour (55%) decrease of rig time per run. Additionally, less torque at higher rotary speeds was seen on the wells in which the vibratory tool was run. The associated physics, operating methodology and effectiveness of these tools will also be presented.

Porosity is a key reservoir property used in petrophysical evaluations. Obtaining realistic porosity estimates in unconventional reservoirs is challenging using only conventional logs. Conventional log porosity measurements are affected by the presence of kerogen in organic-rich reservoirs. Techniques such as ΔLogR can be used to predict total organic carbon (TOC) which can be converted to kerogen volume. The kerogen volume can then be used to apply corrections to conventional porosity measurements. However, these techniques require prior knowledge of thermal maturity or core measurements such as vitrinite reflectance (Ro). The predicted TOC can also be used in conjunction with geochemical elemental measurements for a more accurate assessment of formation kerogen and mineralogy, as well as for hydrocarbon volumes. Nuclear magnetic resonance (NMR) logs measure only the fluids present and represent a total porosity unaffected by solid components such as kerogen and bitumen. Recent observations in numerous unconventional resource plays indicate that NMR log porosity provides the best match to core porosity and does not require corrections for kerogen. NMR log porosity is available in real time as an input to the petrophysical model long before core measurements can be completed. The complex refractive index method (CRIM) in conjunction with mineralogy log data can be used to compute accurate dielectric porosities, which exclude both kerogen and hydrocarbon. Integrating core TOC, predicted TOC, mineral analysis, NMR, and dielectric information, a final verification of the kerogen volume, porosity, hydrocarbon content, and mineral analysis can be assessed. Based on previous work in the Eagle Ford Shale, a comprehensive workflow was developed for unconventional source rock reservoir interpretation. The workflow integrates conventional logs, a geochemical log, an NMR log, and a dielectric log to predict TOC, kerogen volume, mineralogy, total porosity, and hydrocarbon volume. This paper will show results from the Eagle Ford wells upon which this workflow is based. Then, we apply the workflow to the Utica-Point Pleasant Shale Play and compare those results to core measurements.