Steam injection has been the thermal Enhanced Oil Recovery (EOR) to develop heavy and extra heavy crude oil reservoirs worldwide. However, oil price volatility, trends in the energy transition, and steam injection carbon footprint are influential factors limiting the commercial deployment of steam-based EOR technologies. In response to these new challenges, hybrid steam methods such as cyclic steam stimulation (CSS) with preformed foam have become energy and environmentally efficient technology revitalizing mature wells in Colombia.
Since mid-2019, six field tests of preformed foam injection previous to the steam cycle have been implemented to optimize CSS processes in mature wells (> 10 cycles) of a heavy oil field located in the Middle Magdalena Valley (MMV). The technology includes injecting the foaming agent with nitrogen as non-condensable gas using a specially designed wellhead mixer that can generate a stable foam at the surface and inject it as a diverting agent before the steam cycle is injected.
This paper describes the field test evaluation from design to production performance, including foam formation monitoring strategies based on produced water geochemistry. Results will also be described in terms of energy efficiency (E.E.) and carbon intensity (C.I) indexes, defined as criteria to evaluate potential development plans in different assets of the MMV.
The first two pilot wells initiated last July 2019 have reported incremental oil recoveries that exceed 20 KBO. As of October 2021, one of the wells is still producing above the baseline, representing an improvement in E.E. and C.I. Once the baseline production is reached, a second CSS with foam is scheduled as part of the EOR program. In December 2020, two additional tests were implemented. Higher steam injection pressures were observed, suggesting the flow diversion to lower permeabilities and unswept oil intervals as recorded during the first pilot wells. Both wells are showing encouraging performance, and results will also be described. Regarding the geochemical analysis, the increase in the total concentration of water-soluble organic compounds (WSOC) confirms the production of unswept zones within the pay interval. Specific WSOC were identified (i.e., Ox and OxS classes, where X ≥ 2, detected by (-)ESI FT-ICR-MS) as natural tracers to complement ongoing project interpretation. Based on the results observed, different development scenarios are under consideration.
This study provides new insights to optimize CSS in mature wells operating since the early 1980s supported by a novel surface foam generator, affordable monitoring strategies, and developed energy efficiency indexes aligned with lower carbon footprint goals established in Colombia in the era of the energy transition.
382 Background: Bladder carcinoma is the fifth most common neoplasm in developed countries. When muscle-invasive disease is diagnosed in a localized stage, radical cystectomy is the standard treatment, with or without perioperative chemotherapy. In this retrospective study we aim to identify presurgical factors that correlate with relapse risk and survival in patients being treated with radical cystectomy without neoadjuvant chemotherapy. Methods: Patients with a history of radical cystectomy for non-metastatic muscle-invasive bladder carcinoma from 1995 to 2010 were included. They had to have an appropriate follow-up, and tissue available for further correlative studies. Demographic baseline features and therapy outcomes were collected in a retrospective fashion. Results: A total of 158 patients were included, with a median overall survival (OS) for the entire cohort of 51 months (95% IC: 17.1–84.9 months). Median relapse free survival (RFS) is 39 months (95% IC: 3.8–74.1 months). In univariate analysis, the following features were prognostic factors for RFS: ECOG performance status (0 vs ³1; 72 vs 20 months, p=0.014), hemoglobin levels (normal vs low; 144 vs 21 months, p=0.001), free surgical margins (yes vs no; 39 vs 11 months, p=0.004), lymph node status (pN0 vs pN+; 119 vs 18 months, p<0.001) and pT stage (pT2 vs pT3-4; 167 vs 20 months, p< 0.001). Other previously described factors, such as neutrophil-lymphocite ratio, thrombocytosis, creatinine clearance or the presence of hydronephrosis, were not significant in our group of patients. In the multivariate analysis, only ECOG (HR 2.32), lymph node status (HR 2.0) and hemoglobin levels (HR 1.71) were independent predictors for RFS. Conclusions: In our group of patients, apart from ECOG performance status and lymph node status, the presence of presurgical anemia could be an indicator of poorer outcomes after cystectomy. These patients should be monitored closely and maybe considered for further therapeutic procedures, such as adjuvant systemic therapy.
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