Utilizing Simultaneous Capture of T1 and T2 NMR Data to Solve Reservoir Evaluation Issues
Ronald J. Marchel1, Charles H. Smith2, and Sandeep Ramakrishna3
1Marathon Oil Company, Oklahoma City, OK
2Halliburton Energy Services, Oklahoma City, OK
3Halliburton Energy Services, Houston, TX
Deep basin drilling along the Wichita Mountain front in the Anadarko basin of Western Oklahoma poses one of the most difficult log interpretation issues anywhere. Advances in the acquisition and processing of 3-D seismic, has allowed drilling and production of targets that could not previously have been imaged. While the increase in the ability to achieve the desired objective horizon in the well has enhanced prospect economics, the petrophysical evaluation of prospective zones has never been straight forward.
Well to well correlations are difficult due to rapid facies changes in the Pensylvanian Granite Wash along with complex folding and faulting in deeper horizons along the Wichita Mountain Front. Nearby wells are many times not connected due to the rapid facies changes and intense faulting and folding. High density/neutron porosities do not relate directly to permeability, nor does high resistivity relate directly to hydrocarbon production.
Advances in analysis of NMR T2 data allowed producibility (permeability) to be extracted from this data. Measurements of NMR T1 data has provided an excellent approximation of fluid typing. Work began to arrive at a useful solution that would provide these data in a continuous logging pass.
The algorithm that was developed, simultaneously measures these data (T1 and T2) in a usable form and allows correct evaluation of the permeability and reservoir fluid type, thus greatly enhancing the economics of well drilling and completion.
AAPG International Conference and Exhibition, Cape Town, South Africa 2008 © AAPG Search and Discovery