Estimated ultimate recovery (EUR) and well economics are two subjects of high interest for unconventional wells, especially during the downturn of the market when the profitability of unconventional oil/gas becomes marginal. In this work, the authors investigated a few models that are commercially available for EUR assessment and developed a mathematical model for evaluating shale oil economics. EUR is typically assessed by a Decline Curve Analysis (DCA). The authors applied different models (including Arps’ and multi-segment) to estimate EURs. The influence of the length of production data on EUR is also analyzed. A comprehensive approach was taken to analyze all major costs that occur in every phase from leasing to well abandonment. Eventually, a mathematical model is established which enables the estimation of well economics by use of publicly available data, e.g., production data, well total depth, and stimulation treatment. By applying the estimated EURs in the newly developed model, the authors analyzed the economics of more than 3900 shale oil wells in Eagle Ford and Bakken. Results show that the mean breakeven oil prices in Eagle Ford and Bakken are, respectively, $69/bbl and $63/bbl. At an oil price of $50/bbl, more than 60% of the wells in those two shale plays are not profitable.

Operators producing hydrocarbons from conventional and unconventional wells often encounter interconnected production-related challenges that exacerbate one another. Challenges during production include the corrosion of steel caused by acid gases, as well as the precipitation and accumulation of iron sulfide, calcium carbonate scale, and barium sulfate scale. The accumulation of solids on pipe walls can facilitate under-deposit corrosion and plugging. Each of these issues can lead to failures and costly workovers. To address these issues, current treatment approaches require multiple chemical applications, frequent batch treatments, mechanical intervention, or a combination of approaches. In certain scenarios, these approaches can be impractical, ineffective, and/or uneconomical. The objective of this study was to develop a solution to overcome the aforementioned production challenges simultaneously and continuously with a single chemical application. The design strategy was to formulate chemicals that included a variety of chemistries to inhibit multiple corrosion mechanisms, as well as an iron sulfide dissolver, and a scale inhibitor to inhibit the formation of calcium carbonate and barium sulfate scales. Laboratory tests were conducted to demonstrate that the formulations could function in the aforementioned areas. One formulation was then applied in the field under different production scenarios: oil wells equipped with either a gas lift mechanism or an electrical submersible pump. Data from those situations are presented to demonstrate the field performance of the new formulation. Compared to the benchmark chemical treatment efforts, application of the formulation improved or maintained similar corrosion control, reduced or eliminated the accumulation of iron sulfide solids in the well, and improved scale control in each of the production scenarios. This paper presents a viable option for effectively treating common production challenges simultaneously and with one chemical application, which is particularly useful when it is impractical or uneconomical to employ multiple chemical treatments.