Robust and Flexible Hydrocarbon Production Forecasting Considering the Heterogeneity Impact for Hydraulically Fractured Wells

Producing oil and gas from increasingly more difficult reservoirs has become an unavoidable challenge for the petroleum industry because the conventional hydrocarbon resources are no longer able to maintain the production levels corresponding to the global energy demand. As the industrial investments in developing lower permeability reservoirs increase and more advanced technologies, such as horizontal drilling and hydraulic fracturing, gain more attention and applicability, the need for more reliable means of production forecasting also become more noticeable. Production forecasting of hydraulically fractured wells is challenging, particularly for heterogeneous reservoirs, where the rock properties vary dramatically over short distances, significantly affecting the performance of the wells. Despite the recent improvements in well performance prediction, the issue of heterogeneity and its effects on well performance have not been thoroughly addressed by the researchers and many aspects of heterogeneity have yet remained unnoticed. In this paper, a novel empirical approach for production forecasting of multi-fractured horizontal wells is presented in an attempt to effectively include the effect of heterogeneity. This approach is based on the integration of hyperpolic decline curve analysis (DCA) and heterogeneity impact factor (HIF). This newly defined ratio quantifies the heterogeneity impact on the hydraulically fractured well performance and is calculated on the basis of net pressure match interpretation and post-fracture well test analysis. The proposed approach of the decline curve using heterogeneity impact factor (DCH) is validated against data from a southern North Sea field. The results show a maximum of 15% difference between the outcome of the proposed method and the most detailed three-dimensional history-matched model, for a 15 year period of production forecasts. DCH is a novel, fast, and flexible method for making reliable well performance predictions for hydraulically fractured wells and can be used in forecasting undrilled wells and the range of possible outcomes caused by the heterogeneity

Oral Vitamin D Supplementation and Clinical Outcomes of Intravitreal Bevacizumab Injection for Macular Edema Secondary to Retinal Vein Occlusions

Purpose: To evaluate the therapeutic response of retinal vein occlusion (RVO) to intravitreal bevacizumab (IVB) with and without concomitant vitamin D supplementation. Method: Seventy eyes of 68 patients with macular edema associated with branch retinal vein occlusion (BRVO) and central retinal vein occlusion (CRVO) received three monthly IVB injections. Patients with serum 25-hydroxyvitamin D (25(OH) D) higher than 30 ng/ml were considered as the sufficient group. Cases with serum 25(OH) D levels below 30 ng/ml were randomized into the treatment and control groups. The control group received 50,000 IU of oral vitamin D, weekly for two months. One month after the last IVB injection, best-corrected visual acuity (BCVA) and central macular thickness (CMT) were measured and compared with the preinjection values. Results: While 43 eyes (61.4%) of 42 patients had BRVO, 27 eyes (38.6%) of 26 patients had CRVO. In BRVO patients, changes of CMT and BCVA were not significantly different between the sufficient, control, and treatment groups (P = 0.58 and 0.64, respectively). In the CRVO group, CMT reduction in the control group was significantly less than the sufficient and treatment groups (P = 0.048). In addition, improvement of BCVA in the control group was significantly less (P = 0.036) than the sufficient and treatment groups. Conclusion: Oral vitamin D supplement therapy may improve anatomical and functional outcomes in patients with CRVO and vitamin D deficiency

Modeling the Risk of Commercial Failure for Hydraulic Fracturing Projects Due to Reservoir Heterogeneity

Hydraulic fracturing technologies play a major role in the global energy supply and affect oil pricing. The current oil price fluctuations within 40 to 55 USD per barrel have caused diminished economical margins for hydraulic fracturing projects. Hence, successful decision making the for execution of hydraulic fracturing projects requires a higher level of integration of technical, commercial, and uncertainty analyses. However, the complexity of hydraulic fracturing modeling, and the sensitivity and the effects of uncertainty of reservoir heterogeneity on well performance renders the integration of such studies rather impractical. The impact of reservoir heterogeneity on hydraulic fracturing performance has been quantified by the introduction of Heterogeneity Impact Factor (HIF) and formulas have been developed to forecast well performance using HIF. These advances provide a platform for introducing a practical approach for introducing the Risk of Commercial Failure (RCF) due to reservoir heterogeneity in hydraulic fracturing projects. This paper defines such a parameter and the methodology to calculate it in a time-efficient manner. The proposed approach has been exercised on a real project in which a RCF of 20% is computed. The analysis also covers the sensitivity on Capital Expenditure (CAPEX), Operational Expenditure (OPEX), gas price, HIF and discount rate

Perceived Attentional Function and Related Factors in Women Following Breast Cancer Surgery

Background: This study examined perceived cognitive function in patients with breast cancer and determined the main predictors of changes in cognitive function following treatment. Methods: The analytical cross-sectional study was performed in this study. 96 women receiving adjuvant treatment after surgery and who had already received adjuvant treatment were included in the study. The convenience sample was selected from the list of patients in Cancer Registry Center, private clinics and the Oncology Ward of Imam Khomeini Hospital in Ardabil, Iran. We used the Attentional Function Index to measure perceived cognitive function. SPSS version 16.0 was used to analyze the data. We used the t-test and analysis of variance to compare the differences in the Attentional Function Index scores to demographic and medical characteristics. Results: The mean Attentional Function Index score was 59.53±1.69. There was a statistically significant difference between the scores in terms of current non-surgical treatment (P<0.000). Regarding the time elapsed after disease diagnosis, the difference between the Attentional Function Index scores was statistically significant (P<0.00). Conclusion: Chemotherapy and hormone therapy can act as risk factors for cognitive impairment in patients with breast cancer