Targeted Technology Applications for Infield Reserve Growth: A Synopsis of the Secondary Natural Gas Recovery Project Research, Gulf Coast Basin

A diverse and vast resource base of 1,295 trillion cubic feet (Tcf) of technically recoverable natural gas resources (including proved reserves, conventional resources, and nonconventional resources) was estimated by the National Petroleum Council (1992) in a recent analysis of domestic petroleum supplies. Of this resource base, 216 Tcf is predicted to be recoverable by reserve appreciation in existing fields in the lower 48 states. The integrated application of concepts and cost-effective technologies from the disciplines of geology, engineering, geophysics, and petrophysics will be required for converting these resources into producible reserves. In the last decade, characterization of the internal geometry of reservoirs, mainly oil reservoirs, has demonstrated a higher degree of compartmentalization than previously recognized. This compartmentalization, other than structural compartmentalization, is primarily a function of the depositional system and, secondarily, of the diagenetic history of the reservoir after deposition. The objective of a current infield reserve growth analysis of nonassociated natural gas reservoirs is to define the potential for incremental gas recovery based on better understanding of depositional and diagenetic heterogeneity within these reservoirs. Natural gas reserve growth (reserve appreciation) in conventional reservoirs has multiple components. Historically, extensions and deeper pool drilling have been the standard approach used by industry to achieve infield reserve additions. Recompletions of existing wells were often made without the concepts of reservoir heterogeneity or compartmentalization as a tool in recompletion strategy. Where significant geologic variation occurs, untapped, incompletely drained, or bypassed reservoir compartments remain to be drained of natural gas by new infield drilling or by recompleting strategically placed development wells. Today infield reserve growth is beginning to be based on an understanding of vertical and lateral heterogeneity that leads to recompletions in bypassed and incompletely drained reservoirs that were not previously recognized. In addition to concepts of reservoir heterogeneity and compartmentalization, new surface and downhole tools are being developed that will enhance the operator's ability to define these resource targets with greater precision and reliability. Examples of these tools now being developed and selectively used include borehole gravity, through-casing resistivity, cross-well geophysics, and surface three-dimensional seismic in the onshore.Bureau of Economic Geolog

Secondary Natural Gas Recovery: Targeted Technology Applications for Infield Reserve Growth: Case Studies Evaluating the Benefits of Secondary Gas Recovery, Onshore Gulf Coast, South Texas

Economic recovery of natural gas in reservoirs with near-tight to conventional porosity and permeability can be improved through geologically based infill-development strategies. Old gas fields may contain new infield reservoirs, incompletely drained reservoir compartments, untapped reservoir compartments, and bypassed reservoirs. These secondary resources may be identified by a combination of log evaluation and production and pressure analyses, and they are controlled by structural and stratigraphic heterogeneity. Many gas fields in the Gulf Coast may contain opportunities for identifying additional gas resources at modest costs. Remaining natural gas in these fields can be contacted either by recompleting existing wells that have bypassed reservoir compartments or by drilling strategically targeted infield wells. Exploration for new, untapped, or incompletely drained reservoir compartments or bypassed gas zones in old fields can be improved by using state-of-the-art formation evaluation tools and engineering, production, petrophysical, and geological analyses. The economics of developing and producing the secondary gas recovery (SGR) resource is evaluated for two producing properties in existing fields. The case I study area (North Mcfaddin field) had total operational and development costs (excluding royalties) of $0.58 per mcf, compared to total costs in case II (Agua Dulce field) of$0.83 per mcf. Future application of SGR concepts and technology to strategically targeted well locations and recompletions could further lower development costs.Bureau of Economic Geolog

Secondary Natural Gas Recovery: Targeted Technology Applications for Infield Reserve Growth in Deltaifc Sand-Rich Low to Conventional Permeability Reservoirs in the Wilcox Group, Lake Creek Field, Texas

The potential for secondary incremental recovery of natural gas exists in complex fluvial-deltaic reservoirs of the Texas Gulf Coast. Four deltaic parasequences were identified using well logs calibrated to cores in the G sandstone. Engineering evaluations of production performance and pressures are compared with reservoir facies; these evaluations demonstrate the importance of identifying reservoir facies in maximizing recovery of natural gas. A well-log-based model to predict the free-water level and effective gas permeabilities was tested and calibrated using Wilcox gas reservoirs. Key reservoir parameters of porosity, water saturation, permeability, and capillary pressure are related in a single equation. Analysis of natural gas reservoirs from the Wilcox Deltaic sandstones in the Houston Embayment (WX-1) in East Texas indicates that reserve growth potential of approximately 60 percent over the current estimate of ultimate recovery is possible in deltaic sandstone reservoirs in the Lake Creek Unit. Detailed geologic, engineering, and petrophysical evaluation of the G sandstone reservoir in the Lake Creek Unit indicates that the maximum additional incremental gas opportunities exist in the flank region adjacent to the area currently developed in the Lake Creek field. The location, number, and economic feasibility of additional wells required to convert this resource to producible reserves were not evaluated.Bureau of Economic Geolog

Secondary Natural Gas Recovery: Targeted Technology Applications for Infield Reserve Growth in Fluvial Reservoirs, Stratton Field, South Texas

Integrated evaluations of geology, geophysics, reservoir engineering, and petrophysics were conducted for mid-Oligocene-age fluvial reservoirs in Stratton field as part of this study. Located in South Texas within the Frio Fluvial-Deltaic Sandstone along the Vicksburg Fault Zone play (FR-4), Stratton field represents a mature gas field with significant opportunities for natural gas reserve appreciation. These fluvial reservoirs exhibit heterogeneity and often contain multiple compartments. The study identifies a considerable potential for reserve appreciation, with documented opportunities for a 100 percent increase in reserves within a large contiguous area of Stratton field, despite 40 years of prior development. Remaining natural gas reserves can be accessed through recompletion of existing wells that have bypassed reservoir compartments or by drilling infield wells to target compartments not effectively drained at current well spacing. Exploration efforts to discover new reservoirs, identify incompletely drained compartments, or tap bypassed gas zones in old fields can benefit from detailed geological studies integrating engineering, petrophysical, and geophysical methodologies. Various geophysical techniques, including 3-D surface seismic, vertical seismic profiling, amplitude versus offset, and 2-D seismic inversion, were utilized to visualize subtle changes in reservoir topology and compartment boundaries at depths as low as 6,800 ft. The study delineates three classes of compartment sizes based on analysis of ten groups of Frio reservoirs. Forward stochastic modeling of maximum gas recovery suggests that well spacings of 340, 200, and 60 acres (or less) offer optimal gas-contact efficiency in large, medium, and small compartment size reservoirs, respectively.Bureau of Economic Geolog

Secondary Natural Gas Recovery: Targeted Technology Applications for Infield Reserve Growth in Fluvial Reservoirs in the Frio Formation Seeligson Field, South Texas

This report summarizes the results of a 3-year research program, including findings from a project experiment site in fluvial reservoirs within Seeligson field. These reservoirs comprise channel-fill and crevasse-splay sandstones, levee siltstones, and floodplain siltstones and mudstones. Despite Seeligson field's poorly contacted reservoir compartments, its potential for secondary gas recovery in the middle Frio Formation is lower compared to other fields in the FR-4 play. Seeligson field features well-connected fluvial sandstones that have been efficiently drained by a relatively higher number of completions. In contrast, many other fields in the play (such as Stratton and Agua Dulce) contain less intensively completed, isolated fluvial sandstones, representing uncontacted reservoir compartments. Differences in fluvial reservoir architecture and completion practices must be considered as an important aspect of any infield exploration program for fields in the FR-4 play and other gas plays.Bureau of Economic Geolog

Pharmacogenetics of Bleeding and Thromboembolic Events in Direct Oral Anticoagulant Users

Publisher Copyright: © 2021 The Authors. Clinical Pharmacology & Therapeutics published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and TherapeuticsThis study aimed to analyze associations between genetic variants and the occurrence of clinical outcomes in dabigatran, apixaban, and rivaroxaban users. This was a retrospective real-world study linking genotype data of three Finnish biobanks with national register data on drug dispensations and healthcare encounters. We investigated several single-nucleotide variants (SNVs) in the ABCG2, ABCB1, CES1, and CYP3A5 genes potentially associated with bleeding or thromboembolic events in direct oral anticoagulant (DOAC) users based on earlier research. We used Cox regression models to compare the incidence of clinical outcomes between carriers and noncarriers of the SNVs or haplotypes. In total, 1,806 patients on apixaban, dabigatran, or rivaroxaban were studied. The ABCB1 c.3435C>T (p.Ile1145=, rs1045642) SNV (hazard ratio (HR) 0.42, 95% confidence interval (CI), 0.18-0.98, P = 0.044) and 1236T-2677T-3435T (rs1128503-rs2032582-rs1045642) haplotype (HR 0.44, 95% CI, 0.20-0.95, P = 0.036) were associated with a reduced risk for thromboembolic outcomes, and the 1236C-2677G-3435C (HR 2.55, 95% CI, 1.03-6.36, P = 0.044) and 1236T-2677G-3435C (HR 5.88, 95% CI, 2.35-14.72, P A (rs4148738) SNV associated with a lower risk for bleeding events (HR 0.37, 95% CI, 0.16-0.89, P = 0.025) in apixaban users. ABCB1 variants are potential factors affecting thromboembolic events in rivaroxaban users and bleeding events in apixaban users. Studies with larger numbers of patients are warranted for comprehensive assessment of the pharmacogenetic associations of DOACs and their relevance for clinical practice.Peer reviewe

Diagnostic accuracy of plasma NT-proBNP levels for excluding cardiac abnormalities in the very elderly

<p>Abstract</p> <p>Background</p> <p>In the elderly the diagnosis of chronic heart failure is often challenging and the availability of echocardiography can be limited. Plasma levels of NT-proBNP are valuable tools to diagnose patients with heart failure. However, the performance of this biomarker to detect cardiac abnormalities in the very elderly remains unclear. The aims of this study were to investigate the relation between NT-proBNP and cardiac abnormalities and to evaluate the use of NT-proBNP to exclude structural and functional cardiac abnormalities in a community-based sample of "well-functioning" nonagenarians.</p> <p>Methods</p> <p>A diagnostic cross-sectional study embedded within the Leiden 85-plus Study in the municipality of Leiden, the Netherlands. Plasma NT-proBNP levels were measured and 2-dimensional echocardiography was performed in a subgroup of 80 well-functioning nonagenarians. Linear regression analysis was used to explore the relation between NT-proBNP and cardiac abnormalities and ROC curve analysis was used to assess the performance of NT-proBNP to exclude cardiac abnormalities. The upper limit of the lowest tertile of NT-proBNP was used as a cut-off value.</p> <p>Results</p> <p>NT-proBNP levels were associated with abnormal left ventricular (LV) dimensions, LV systolic and diastolic function, left atrial enlargement and valvular heart disease. LV mass, E/A ratio and degree of aortic regurgitation were identified as independent predictors of NT-proBNP. NT-proBNP levels were higher with greater number of echocardiographic abnormalities (P < 0.001). A cut-off level of 269.5 pg/mL identified patients with abnormal LV dimensions or depressed LV systolic function (sensitivity 85%, negative predictive value (NPV) 77%, area under the curve 0.75 (95% CI 0.64-0.85)). In addition, high NPV were found for LV systolic dysfunction, left atrial enlargement, severe valvular heart disease and pulmonary hypertension. The test performance of NT-proBNP to exclude any echocardiographic abnormality showed a sensitivity of 82% and a NPV of 65%.</p> <p>Conclusions</p> <p>In this convenience sample of well-functioning nonagenarians NT-proBNP was related to a wide variety of functional and structural echocardiographic abnormalities. Moreover, NT-proBNP could be used to exclude echocardiographic abnormalities in well-functioning nonagenarians and might be used to indicate who needs to be referred for further cardiovascular examination.</p

Estimated GFR reporting is not sufficient to allow detection of chronic kidney disease in an Italian regional hospital

<p>Abstract</p> <p>Background</p> <p>Chronic kidney disease (CKD) is an emerging worldwide problem. The lack of attention paid to kidney disease is well known and has been described in previous publications. However, little is known about the magnitude of the problem in highly specialized hospitals where serum creatinine values are used to estimate GFR values.</p> <p>Methods</p> <p>We performed a cross-sectional evaluation of hospitalized adult patients who were admitted to the medical or surgical department of Santa Maria della Misericordia Hospital in 2007. Information regarding admissions was derived from a database. Our goal was to assess the prevalence of CKD (defined as an estimated glomerular filtration rate [eGFR] < 60 mL/min/1.73 m²) and detection of CKD using diagnostic codes (Classification of Diseases, Ninth Revision, Clinical Modification [ICD-9-CM]). To reduce the impact of acute renal failure on the study, the last eGFR obtained during hospitalization was the value used for analysis, and intensive care and nephrology unit admissions were excluded. We also excluded patients who had ICD-9-CM codes for renal replacement therapy, acute renal failure, and contrast administration listed as discharge diagnoses.</p> <p>Results</p> <p>Of the 18,412 patients included in the study, 4,748 (25.8%) had reduced eGFRs, falling into the category of Kidney Disease Outcomes Quality Initiative (KDOQI) stage 3 (or higher) CKD. However, the diagnosis of CKD was only reported in 19% of these patients (904/4,748). It is therefore evident that there was a "gray area" corresponding to stage 3 CKD (eGFR 30-59 ml/min), in which most CKD diagnoses are missed. The ICD-9 code sensitivity for detecting CKD was significantly higher in patients with diabetes, hypertension, and cardiovascular disease (26.8%, 22.2%, and 23.7%, respectively) than in subjects without diabetes, hypertension, or cardiovascular disease (p < 0.001), but these values are low when the widely described relationship between such comorbidities and CKD is considered.</p> <p>Conclusion</p> <p>Although CKD was common in this patient population at a large inpatient regional hospital, the low rates of CKD detection emphasize the primary role nephrologists must play in continued medical education, and the need for ongoing efforts to train physicians (particularly primary care providers) regarding eGFR interpretation and systematic screening for CKD in high-risk patients (i.e., the elderly, diabetics, hypertensives, and patients with CV disease).</p

Safety of intravenous ferric carboxymaltose versus oral iron in patients with nondialysis-dependent CKD: an analysis of the 1-year FIND-CKD trial.

Background: The evidence base regarding the safety of intravenous (IV) iron therapy in patients with chronic kidney disease (CKD) is incomplete and largely based on small studies of relatively short duration. Methods: FIND-CKD (ClinicalTrials.gov number NCT00994318) was a 1-year, open-label, multicenter, prospective study of patients with nondialysis-dependent CKD, anemia and iron deficiency randomized (1:1:2) to IV ferric carboxymaltose (FCM), targeting higher (400-600 µg/L) or lower (100-200 µg/L) ferritin, or oral iron. A post hoc analysis of adverse event rates per 100 patient-years was performed to assess the safety of FCM versus oral iron over an extended period. Results: The safety population included 616 patients. The incidence of one or more adverse events was 91.0, 100.0 and 105.0 per 100 patient-years in the high ferritin FCM, low ferritin FCM and oral iron groups, respectively. The incidence of adverse events with a suspected relation to study drug was 15.9, 17.8 and 36.7 per 100 patient-years in the three groups; for serious adverse events, the incidence was 28.2, 27.9 and 24.3 per 100 patient-years. The incidence of cardiac disorders and infections was similar between groups. At least one ferritin level ≥800 µg/L occurred in 26.6% of high ferritin FCM patients, with no associated increase in adverse events. No patient with ferritin ≥800 µg/L discontinued the study drug due to adverse events. Estimated glomerular filtration rate remained the stable in all groups. Conclusions: These results further support the conclusion that correction of iron deficiency anemia with IV FCM is safe in patients with nondialysis-dependent CKD