Browsing by Subject "Shale oil"
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Item Eagle Ford shale : evaluation of companies and well productivity(2016-08) Chavez Urbina, Grecia Alexandra; King, Carey Wayne, 1974-; Lake, Larry W.Unconventional resources, particularly shale reservoirs, are a significant component in oil and gas production in the United States as they represent (as of May 2015) 48 and 58 percent, respectively, of the total oil and gas produced. However, there has been a deceleration on oil and gas production in general because of low market prices. The drastic decline in oil and gas prices that started in 2014 has companies struggling to continue their operations, resulting in negative financial outcomes for 2015 for most companies. The present work examines the financial results of three companies, EOG Resources, Pioneer Natural Resources, and Chesapeake Energy, along with their particular well productivity using the Logistic Growth model to forecast production in one of the most prolific shale plays in the United States, the Eagle Ford. This work also examines the economic feasibility of drilling new wells when oil prices are low using a discounted cash flow model for each company. The financial analysis shows that from the three companies, Pioneer Natural Resources has the best financial results; its high cash-flow-to-debt ratio, and low debt and debt-to-equity ratios make it an attractive company to invest in. In contrast, Chesapeake has the worst results which represents high risk for investors, and EOG has moderate results that still make it a good company to invest in. The discounted cash flow model demonstrate that under the cost assumptions and estimated production used in this work, EOG gets the best results from their wells located in the Eagle Ford with break-even prices bordering the 40 $/bbl compared to the other companies with break-even prices above 87 $/bbl for Pioneer and 89 $/bbl for Chesapeake. From the discounted cash flow model, it can also be concluded that none of the companies in the analysis is expected to gain revenue from drilling new wells if oil prices are under 40 $/bbl, and that companies that are quick to respond to the low prices by reducing their drilling and completion costs can significantly improve their well economics.Item Evaluation of EOR Potential by Gas and Water Flooding in Shale Oil Reservoirs(2013-05) Chen, Ke; Sheng, James; Menouar, Habib K.; Heinze, Lloyd R.The demand for oil and natural gas will continue to increase for the foreseeable future; unconventional resources such as tight oil, shale gas, shale oil will pose an irreplaceable role in oil and gas industry to fill the gap between demand and supply. With the relatively modest natural gas price, producing oil from unconventional shale reservoirs, which are less common and less well understood than conventional sandstone and carbonate reservoirs, has attracted more and more interest from oil operators. Through many tremendous efforts on the development of shale resources, the horizontal well-drilling with multiple transverse fractures has proven to be an effective method for shale gas reservoirs exploitation and it has also been used in extracting oil from shale reservoirs by some operators. However, the oil recovery is very low (5-10%). For the important role of shale resources in future oil and gas industry, more stimulation and production strategies must be considered and tested to find better methods to improve oil production from shale reservoirs. Gas flooding and water flooding, relatively simple and cheaper EOR techniques, which have been successfully implemented in conventional and some unconventional tight oil reservoirs for a long time, are considered in our work. A black-oil simulator developed by Computer Modeling Group Ltd was selected in our work. We build a reservoir model of 200ft long, 1000ft wide and 200 ft thick two 1-ft wide ×1000-ft long hydraulic fractures to simulate gas flooding and water flooding in shale oil reservoirs. We first validate a base model, and discussed the determination of miscibility parameter and injection pressure. Production behavior and oil recovery of different plans are discussed through sensitivity studies. Simulation results of primary production, gas injection and water injection are compared in this thesis. Results show that miscible gas injection has better effect on improving oil recovery from shale reservoirs than water injection. Solvent injected into the reservoirs above MMP can be fully miscible with oil, reducing oil viscosity greatly, and can lead a better sweep efficiency besides pressure maintenance. Our simulation results indicate that the oil recovery can be increased up to 15.1% by using gas injection in a hydraulically fractured shale reservoir, compared with the original 6.5% recovery from the primary depletion. This thesis provides a preliminary analysis to regarding the EOR potentials by gas and water flooding in shale oil reservoirs. The results show that miscible gas flooding could be a good prospect in future development of shale oil resources.Item Using simple models to describe oil production from unconventional reservoirs(2014-05) Song, Dong Hee; Lake, Larry W.Shale oil (tight oil) is oil trapped in low permeability shale or sandstone. Shale oil is a resource with great potential as it is heavily supplementing oil production in the United States (U.S. Energy Information Administration, 2013). The shale rock must be stimulated using hydraulic fracturing before the production of shale oil. When the hydrocarbons are produced from fractured systems, the resulting flow is influenced by the fracture, the stimulated rock, and the matrix rock. The production decline rates from shale oil reservoirs experience flow regimes starting with fracture linear flow (fracture dominated), then bilinear flow (fracture and stimulated rock dominated), then formation linear flow (stimulated rock dominated), and finally pseudo-radial flow (unstimulated matrix rock dominated) (Cinco-Ley 1982). In this thesis, daily production rates from a shale oil reservoir are modeled using a simple spreadsheet-based, finite difference serial flow simulator that models the single-phase flow of a slightly-compressible oil. This simulator is equivalent to flow through multiple tanks (subsequent part of the thesis will call these cells) through which flow passes serially through one tank into the other. The simulator consists of 11 tanks. The user must specify the compressibility-pore volume product of each tank and the transmissibility that governs flow from one tank to another. The calculated rate was fitted to the given data using the Solver function in Excel. The fitted matches were excellent. Although we can adjust all 22 parameters (2 per cell) to affect the simulation results, we found that adjusting only the first three cells nearest to the well was sufficient. In many cases, only two cells were enough. Adjusting 4 or more cells resulted in non-unique matches. Furthermore, the properties of the very first cells proved insensitive to the matches when using the 3 cells to match the data. The cells in the 2 cell model represent the stimulated zone and the unstimulated rock. Likewise, the cells in the 3 cell model represent the hydraulic fracture, the stimulated zone, and the unstimulated rock. The accessed pore volume and transmissibility were responsive to the injected sand mass and fluid volume up to approximately 10⁶ kg and 7000 m³ respectively; injecting more sand and fluids than this caused negligible increases in the accessed pore volume and transmissibility. This observation suggests that the sand does not migrate far into the fractures. Similarly, it was observed that the number of stages was positively correlated with cell transmissibility and pore volume up to 20 stages. These results suggest that fracture treatments were significantly over designed and injecting less sand and water in fewer stages would optimize the economics of similar projects. To our knowledge this is the first work to analyze the results of fracture treatments by matching with pore volumes and transmissibility in a simple serial cell flow.