Gas Cap Monitoring in high flow rate, low porosity clastic reservoirs in Colombia gives big economic returns David Bullion; David Bullion BP Exploration Colombia Search for other works by this author on: This Site Google Scholar Fabio Gonzalez; Fabio Gonzalez BP Exploration Colombia Search for other works by this author on: This Site Google Scholar Marvin E. Markley Marvin E. Markley Schlumberger Search for other works by this author on: This Site Google Scholar Paper presented at the SPE Annual Technical Conference and Exhibition, Dallas, Texas, October 2000. Paper Number: SPE-62940-MS https://doi.org/10.2118/62940-MS Published: October 01 2000 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Get Permissions Search Site Citation Bullion, David, Gonzalez, Fabio, and Marvin E. Markley. "Gas Cap Monitoring in high flow rate, low porosity clastic reservoirs in Colombia gives big economic returns." Paper presented at the SPE Annual Technical Conference and Exhibition, Dallas, Texas, October 2000. doi: https://doi.org/10.2118/62940-MS Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex Search nav search search input Search input auto suggest search filter All ContentAll ProceedingsSociety of Petroleum Engineers (SPE)SPE Annual Technical Conference and Exhibition Search Advanced Search AbstractCased hole neutron logging has been around for a long time and is often used to monitor gas movement in reservoirs behind pipe. This often works well in high porosity reservoirs but is rarely successful in low porosity reservoirs. In Colombia, there are high flow rate reservoirs with significant permeability, that have low porosity (5–6 PU).The challenge was to monitor gas cap expansion, fluid movement due to re-injection, and voidage. At the same time the objective was to identify low GOR intervals behind pipe for possible recompletion.A number of different examples are shown to illustrate both the technique and the economic benefit of the monitoring program. Many of these wells contributed significant additional oil from bypassed zones that were initially thought to be dry gas. In some wells, the instantaneous incremental production was ovr 10,000 BOPD from a single recompletion.Gas cap monitoring in very low porosity reservoirs in Colombia proved to be not only feasible, but extremely profitable by differentiating dry gas zones from low GOR zones.Introduction-Cusiana Field, ColombiaCusiana is a field in Colombia (Figure 1) that produces high rates of oil and gas from sandstone formations in the Andes foothills. Tectonic evolution of the area dates back to an early Paleozoic rifting period forming grabens where a thicksequenceofsedimentswasdeposited. The Llanos (which is the current plains area east of the Andes in Colombia) was an extensional subsidence basin in the Triassic and early Cretaceous, becoming a passive subsidence basin in the late Cretaceous (Figure 2).Tertiary, Cretaceous and Paleozoic silico-clastic sedimentary sequences overlie the pre-Cambric basement consisting of crystalline and metamorphic rocks. The maximum sedimentary thickness reaches 12,000 m.(40,000 feet). Keywords: colombia, count rate, reservoir, log analysis, intervention, upstream oil & gas, crossover, ap monitor log, drillstem/well testing, low porosity clastic reservoir Subjects: Formation Evaluation & Management, Open hole/cased hole log analysis, Drillstem/well testing This content is only available via PDF. 2000. Society of Petroleum Engineers You can access this article if you purchase or spend a download.