Abstract

This study uses microscopic, mesoscopic, and macroscopic data to characterize the depositional environments and reservoir distribution of the Ramsey Sand of the Bell Canyon Formation in the Paduca Field, Lea County, New Mexico. For various reasons, projected recovery in the field has underperformed. The Paduca is the largest field in size (but not production) of the Bell Canyon Formation in this portion of the basin, therefore, increasing recovery in the area is potentially quite lucrative. The study describes previous works in academia and industry that aim to study the Bell Canyon formation, but none of these target the Paduca Field itself.

Four cores were described and the various facies extrapolated into comprehensive graphic logs and tied to well logs in the field. The subsurface geometry of the Paduca Field was evaluated in great detail as the interplay of interbedded silts with sandstone, structural pinch outs, hydrodynamic complexity, localized concretions of calcite cements and other barriers to flow affect local recovery. Gamma-ray and acoustic logs were the primary electric logs tool in the development of the field and tying the core descriptions and facies analysis to the logs enabled the identification of two productive sands in the field. Utilizing a series of cross sections through the field to correlate the productive sands and the barriers separating the sands, a series of structure and isopach maps were constructed. Evaluation of these maps document: two periods of channel fill that are offset to each other; that the thickest sand is not located at the present structural crest of the field; and the geometry of the field indicated Laramide and Basin and Range tilting had greatly affected the oil-water contacts.

During thin section analysis, a rapid, accurate microscopic technique was developed to identify feldspars where no preparation (staining) had been performed. Using longwave light-emitting diode (LED) ultraviolet light in conjunction with the incandescent light, it was discovered that the feldspars, altered feldspars and quartz in the arkose to sub-arkose sands were easily to identify with mineral fluorescence. This method was then used to make rapid estimations of the mineralogy of the sands.

This method of microscopic study, together with megascopic and macroscopic observations and knowledge of reservoir formation helped create a clearer picture of the Paduca Field, which in turn, can lead to increase recovery in this field and others like it.