石油工程师协会技术年会论文spe166198

Copyright 2013, Society of Petroleum Engineers This paper was prepared for presentation at the SPE Annual Technical Conference and Exhibition held in New Orleans, Louisiana, USA, 30 September–2 October 2013. This paper was selected for presentation by an SPE program committee following review of information contained in an abstract submitted by the author(s). Contents of the paper have not been reviewed by the Society of Petroleum Engineers and are subject to correction by the author(s). The material does not necessarily reflect any position of the Society of Petroleum Engineers, its officers, or members. Electronic reproduction, distribution, or storage of any part of this paper without the written consent of the Society of Petroleum Engineers is prohibited. Permission to reproduce in print is restricted to an abstract of not more than 300 words; illustrations may not be copied. The abstract must contain conspicuous acknowledgment of SPE copyright.
Abstract Due to their simplicity, empirical production forecasting methods have been used by the petroleum industry for decades. Since 2008, a number of empirical methods have been introduced to the petroleum industry, specifically for wells located in tight/shale reservoirs. However, most of these new methods are not reliable for forecasting remaining reserves, although they may appear to be very good for forecasting EUR in wells in which a high percentage of the EUR has already been produced. The Stretched Exponential Production Decline (SEPD) Method was introduced in 2010. Our results from analysis of both synthetic and actual field data by using SEPD have indicated that this method will most likely underestimate EUR in reservoirs with permeability ranging from 0.1mD to 0.0001mD. A modified SEPD (YM-SEPD) Method has therefore been developed to eliminate the SEPD Method’s shortcoming by employing a new specialized plot to find all related parameters. This newly developed method is very easy to use and, most importantly, it will yield a much more reliable production and remaining reserve prediction for tight horizontal wells. With longer production histories, remaining reserves can be forecasted even more accurately and with a high confidence level. Hundreds of horizontal wells including oil wells from various formations (Cadomin, Montney, Notikewin, Cardium, Barnett Shale, Muskwa, etc.), hydraulically fractured in various ways, have been analyzed using the modified SEPD (YM-SEPD) method. Results indicate that reliable EURs and production profiles can be predicted readily for wells having only two to three years of production history. For wells having less than two years of production history, the modified SEPD (YMSEPD) Method can also yield reasonable production forecasts when coupled with Duong’s empirical method. This paper presents the application of the modified SEPD (YM-SEPD) Method to a number of actual and synthetic oil and gas wells to estimate their proved reserves, including horizontal wells producing dry, wet and retrograde gas as well as tight oil. These examples have had production histories with either observed or non-observed boundary-dominated flow (BDF). The examples also illustrate how the modified SEPD (YM-SEPD) method is capable of estimating proven reserves with high confidence. Introduction As a general rule in North America, operators of oil and gas wells are required by law to perform an annual reserves updates on their wells, both newly drilled and existing wells. For operators whose securities are listed on U.S. Exchanges, the Securities and Exchange Commission (SEC) has clearly stated that proved developed producing reserves (PDP) are “those quantities of oil and gas, which, by analysis of geoscience and engineering data, can be estimated with reasonable certainty to be economically producible, from a given date forward…that the quantities actually recovered will equal or exceed the estimate.” As such, initial reserve bookings tend to be conservative in relation to the projected range of uncertainty. However, uncertainty typically diminishes with more data (time) becoming available. As a result, additional PDP reserves can be booked. In other words, we should expect that the estimation of EUR will increase over time, especially during early stages of production life.
SPE 166198 Estimating Proved Reserves in Tight/Shale Wells Using the Modified SEPD Method
Shaoyong Yu, ConocoPhillips Canada; W. John Lee, University of Houston; Dominic J. Miocevic, ConocoPhillips Canada; Dong Li, University of Houston; Seth Harris, Texas A&M University
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SPE 166ຫໍສະໝຸດ Baidu98
In recent years, the estimation of EUR for horizontal wells with multi-stage fractures in tight/shale reservoirs has been a real challenge facing reservoir engineers, mainly due to complexities in both reservoir and near-well flow regimes. In industry today, the most common methods to estimate EURs are analytical (Bello, and Wattenbager, 2008, 2009, 2010; Anderson, et al, 2010), numerical (Cipolla, et al, 2009), or empirical (Arps, 1945; Ilk, et al, 2009). All three approaches have their advantages and disadvantages. Empirical methods, due to their simplicity, remain the most widely used approach in industry. Therefore, a few methods (Valko, 2009; Duong, 2010) have been developed and recommended by experts for wells in tight/shale reservoirs (Lee, 2012a, Lee, 2012b). Unfortunately, most of these new methods are not proved to be reliable for estimating remaining reserves using only data from a well’s early production history (Yu, 2013). They appear to be most suitable for forecasting EUR in wells from which a high percentage of the EUR has already been produced (Yu, 2013). This paper presents the application of a new methodology: a modified SEPD (YM-SEPD) Method to estimate proved reserves using data from early well history. The method is applicable to horizontal wells producing dry, wet or retrograde gas as well as tight oil. The method has been tried on a number of wells having production histories with or without boundary-dominated flow (BDF). These examples also illustrate how the modified SEPD (YM-SEPD) Method is capable of estimating proven reserves that strictly following the definition of PDP from the SEC perspective. The Modified Stretched Exponential Production Decline Model (YM-SEPD) To predict production profiles and EURs of tight/shale wells, Valko et al. (Valko, 2009; Valko, et al., 2010) proposed the Stretched Exponential Production Decline (SEPD) method as follows: Gas or oil rate: