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Formation evaluation using wireline logs in shale-gas or source-rock reservoirs can be complicated by the presence of total organic carbon (TOC) and, at times, rapidly varying mineralogy. If not properly accounted for, both can result in erroneous calculations of porosity and free-gas and adsorbed-gas volume. When core data, such as mineralogy, porosity, TOC, and elastic properties, are available from a large multiwell database, it is possible to extract reliable statistical relationships among properties. This paper documents a workflow to apply these relationships to other wells using wireline logs.
- North America > United States > Texas (0.30)
- North America > United States > Louisiana (0.30)
- Geology > Mineral (1.00)
- Geology > Geological Subdiscipline (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.68)
- North America > United States > Texas > Haynesville Shale Formation (0.99)
- North America > United States > Louisiana > Haynesville Shale Formation (0.99)
- North America > United States > Arkansas > Haynesville Shale Formation (0.99)
Abstract When evaluating mud rock completions one is quickly struck with the complexity of the task. Mud rock "shales" by their very nature can be problematic to evaluate given the wide variation in geology, rock properties, and reservoir characteristics, not to mention the effect of multi-fractured horizontal well completions. Quite often, the reservoir characteristics between an economic well and an uneconomic well are very similar, further compounding the problem. So, what can we learn by taking another look at North American shale plays to help identify the more productive shales, improve economics and reduce the cycle time bringing this resource to market globally? Sometimes, the simple measurements we make at the wellsite can be very indicative of the things we don't measure very well, like the degree of natural fracturing and the interconnectedness of porosity. The subject material and the information discussed in this review was derived from the study of the characteristics and data from hundreds of completions with production results for shale wells in North America. The findings presented show the results of formation evaluation and analytical evaluation which have proven to be good indicators of well productivity and hydrocarbon recovery. Many of these methods have been underutalized by the industry for shale evaluation and completion optimization. Past successes in unconventional resource arenas are sometimes viewed as the result of seredipity. However, that has not been the case โ past successes have evolved, in some cases over periods of years. A comparison of learnings from the Bakken and Eagle Ford show some interesting commonalities that help identify economic wells from subeconomic wells, as well as the most productive completion intervals in lateral wellbores. These findings and evaluation methodologies can readily contribute to the global hunt for unconventional reservoirs, and evaluation / optimization of their development strategy..
- North America > United States > Texas (1.00)
- North America > United States > North Dakota (1.00)
- Europe (0.93)
- (2 more...)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (1.00)
- Geology > Petroleum Play Type > Unconventional Play > Shale Play (1.00)
- Geology > Geological Subdiscipline (1.00)
- North America > United States > Texas > Fort Worth Basin > Barnett Shale Formation (0.99)
- North America > United States > North Dakota > Parshall Field (0.99)
- North America > United States > California > San Joaquin Basin > Elk Hills Field (0.99)
- (34 more...)
- Well Drilling > Drilling Operations > Directional drilling (1.00)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Shale oil (1.00)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Shale gas (1.00)
- Management > Energy Economics > Unconventional resource economics (1.00)
A Case Study on Formation Evaluation of Horizontal Wells in the Tight Gas Nikanassin Group of the Western Canada Sedimentary Basin Using Drill Cuttings
Olusola, Bukola K. (Schulich School of Engineering, University of Calgary) | Aguilera, Roberto (Schulich School of Engineering, University of Calgary)
Abstract The use of drill cuttings has evolved recently from qualitative to quantitative evaluations due to the possibility of measuring porosity and permeability from drill cuttings in the laboratory with a good level of certainty. One of the advances has been the implementation of complete quantitative formation evaluation for vertical wells from drill cuttings only in the absence of well logs. This paper uses the same methodology in the case of a horizontal well. The case study is demonstrated with the use of sixty five (65) drill cuttings samples collected over 760 meters of a horizontal well drilled through the Monteith formation, Nikanassin group of the western Canada sedimentary basin (WCSB). Starting with only drill cuttings measurements of porosity and permeability in the laboratory, the method allows a successive approach for determination of several parameters of interest including pore throat aperture radius, water saturation, porosity exponent (m), true formation resistivity, Knudsen number, capillary pressure, construction of Pickett plots, and the estimation of geomechanical properties such as Young Modulus, Poissonโs ratio and brittleness index throughout the horizontal length of the well. And for those cases where there is close to no data at all in the Nikanassin formation, empirical correlations have been developed for estimating Poissonโs ratio, static Young Modulus and brittleness index with the use of only porosity from drill cuttings. The correlation coefficient (R) in this case is 0.99. It is concluded that drill cuttings provide a useful direct source of information for quantitative formation evaluation of horizontal wells particularly in those cases where core and log data are scarce.
- North America > Canada > British Columbia (1.00)
- North America > Canada > Alberta (1.00)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.47)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock (0.46)
- North America > United States > Texas > Fort Worth Basin > Barnett Shale Formation (0.99)
- North America > United States > Oklahoma > Anadarko Basin > Cana Woodford Shale Formation (0.99)
- North America > United States > Montana > Red Rock Field (0.99)
- (8 more...)
Integrated Unconventional Play Solution โ A Case Study in Developing Very Thin Low-Permeability Gas Reservoir and Shale Gas Reservoir in Sichuan Basin, Central China
Qiang, Jiang Yu (Southwest Petroleum University) | Run, Peng Hai (PetroChina SWOGC ShuNan) | Yang, Yang (PetroChina SWOGC ShuNan) | Halomoan, Parlindungan Monris (Schlumberger) | Zhao, Jing Kai (Schlumberger) | Wang, Yue (Schlumberger)
abstract Exploration and production of unconventional reservoirs have been conducted in the Sichuan basin since the 1950s. In that time, the relatively thicker low-permeability (tight) gas reservoirs have been developed, and a very thin tight reservoir and a shale gas reservoir are now being targeted. An operator has planned to develop these unconventional reservoirs with long horizontal drilling combined with multistage hydraulic fracturing. However, the management of the subsurface uncertainties appears as the biggest challenge. Since the basin rests in a major compressional tectonic area, the target reservoirs are very sensitive to abrupt structural dip changes and faulted standoffs. Precise landing and lateral placement of horizontal wells are critical to the success of this program. Advanced logging-while-drilling (LWD) acquisition and real-time data transmission have been applied to overcome these challenges. A new LWD imaging technology delivers high-resolution electrical borehole images, azimuthal gamma ray, and multidepth measurement of formation resistivity for well placement and fracture identification purposes in the thin tight gas reservoirs. A multifunction LWD formation evaluation delivers the elemental capture spectroscopy in addition to triple- combo measurements for well placement and real-time formation evaluation in the shale gas reservoir. Based on these real-time data and advanced interpretation or analysis techniques while drilling, structural features including dips, faults, and fractures could be clearly identified. Improved elemental composition from elemental capture spectroscopy and enhanced formation grain density evaluation could also be obtained. As a result, the team has been able to accurately place the well and significantly reduce the probability of erroneous lateral placement and optimize the completion design and planning of the hydraulic fracturing staging and segmentations. The successful implementation of this solution has led to the conclusion that the very thin tight gas reservoir and shale gas reservoir can be profitably developed in Sichuan Basin.
- Geology > Structural Geology (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (1.00)
- Geology > Geological Subdiscipline (1.00)
- Geophysics > Seismic Surveying > Borehole Seismic Surveying (1.00)
- Geophysics > Borehole Geophysics (1.00)
Abstract When evaluating mud rock completions one is quickly struck with the complexity of the task. Mud rock "shales" by their very nature can be problematic to evaluate given the wide variation in geology, rock properties, and reservoir characteristics, not to mention the effect of multi-fractured horizontal well completions. Quite often, the reservoir characteristics between an economic well and an uneconomic well are very similar, further compounding the problem. So, what can we learn by taking another look at North American shale plays to help identify the more productive shales, improve economics and reduce the cycle time bringing this resource to market globally? Sometimes, the simple measurements we make at the wellsite can be very indicative of the things we don't measure very well, like the degree of natural fracturing and the interconnectedness of porosity. The subject material and the information discussed in this review was derived from the study of the characteristics and data from hundreds of completions with production results for shale wells in North America. The findings presented show the results of formation evaluation and analytical evaluation which have proven to be good indicators of well productivity and hydrocarbon recovery. Many of these methods have been underutalized by the industry for shale evaluation and completion optimization. Past successes in unconventional resource arenas are sometimes viewed as the result of seredipity. However, that has not been the case โ past successes have evolved, in some cases over periods of years. A comparison of learnings from the Bakken and Eagle Ford show some interesting commonalities that help identify economic wells from subeconomic wells, as well as the most productive completion intervals in lateral wellbores. These findings and evaluation methodologies can readily contribute to the global hunt for unconventional reservoirs, and evaluation / optimization of their development strategy..
- North America > United States > Texas (1.00)
- North America > United States > North Dakota (1.00)
- Europe (0.93)
- (2 more...)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (1.00)
- Geology > Petroleum Play Type > Unconventional Play > Shale Play (1.00)
- Geology > Geological Subdiscipline (1.00)
- North America > United States > Texas > Fort Worth Basin > Barnett Shale Formation (0.99)
- North America > United States > North Dakota > Parshall Field (0.99)
- North America > United States > California > San Joaquin Basin > Elk Hills Field (0.99)
- (34 more...)
- Well Drilling > Drilling Operations > Directional drilling (1.00)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Shale oil (1.00)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Shale gas (1.00)
- Management > Energy Economics > Unconventional resource economics (1.00)
Revolution of Horizontal Well Formation Evaluation To Promote the Deep and Complex Reservoir Development - Case Studies from Tarim Basin, China
Wen, Xiao Cheng (PetroChina Tarim Oilfield Company) | Tong, Fan Wen (PetroChina Tarim Oilfield Company) | Yi, Zhu (PetroChina Tarim Oilfield Company) | Bin, Nie Xiang (Schlumberger) | Han, Shim Yen (Schlumberger) | Jun, Zhao Li (Schlumberger)
Abstract The development of the Tarim Basin had been lagged behind because of its unique reservoir characteristics and notorious drilling conditions. The main challenges faces by operators can be grouped into three areas:Deep reservoir; Poor borehole condition; Complex relationship between logging response and reservoir characteristics. The constraint of these challenging environments along with traditional logging limitation restrained the formation evaluation of these complex reservoirs. At the same time, the lack of information in this area resulted in "blind" drilling where limited logging devices were allowed in BHA under such high risk environment. Bad borehole condition had also negatively impacted the logging data quality acquired after drilling. This situation formed a vicious cycle and has tremendously obstructed the final reservoir development in this area. Pilot projects had been initialized to evaluate and select suitable LWD measurements to address these problems. This paper describes how those LWD technologies were applied in Tarim innovatively to solve the respective problems. These examples showed an evolutional step had been taken placed in horizontal well evaluation in promoting the deep and complex reservoir development in Tarim basin.
- Asia > China > Xinjiang Uyghur Autonomous Region > Tarim Basin > Lunnan Field (0.99)
- North America > United States > Louisiana > China Field (0.97)
- Information Technology > Knowledge Management (0.40)
- Information Technology > Communications > Collaboration (0.40)
Technology Focus When interviewing potential senior-petrophysicist recruits, we exchange pleasantries to break the ice and then I ask an easy, yet fundamental technical question: โHow would you explain Archieโs law to an inexperienced colleague?โ Then, I sit back in expectation of a slick answer from the candidate. Imagine my surprise when the interviewee takes a sharp intake of breath, looks up at the ceiling, scratches his head, and, finally, exhales audibly before launching into a ramble with more โerrsโ than a David Beckham post-match press conference. โSorry, I do know it. Honestly, I use it every day in my petrophysical interpretation program. Itโs just that I havenโt been asked to describe it before. Sorry,โ mumbles the candidate. Unfortunately, the scene I have just described is an all-too-common one. I was genuinely taken aback that some experienced petrophysicists were unable to state Archieโs law chapter and verse. I was expecting to hear something like, โArchieโs law relates the in-situ electrical conductivity of a sedimentary rock to its porosity and brine saturation. It is purely empirical, describing ion flow (mostly sodium and chloride) in clean, consolidated sands, with varying intergranular porosity of moderate to high values. Electrical conduction is assumed not to be present within the rock grains or in fluids other than water.โ Hence, I was gladdened by the news that, from next September, the University of Aberdeen in Scotland is to offer a masterโs degree in petrophysics and formationย evaluation. Hopefully, the next generation of petrophysicists not only will answer my question without hesitation but also will appreciate the danger of blindly applying Archieโs law. At a recent conference organized by the London Petrophysical Society to celebrate 70 years since Gus Archie gave his seminal paper, attendees were reminded of the various influences on calculated water saturation. It was shown that, with a classic Archie rock of 20% porosity and formation and water resistivities of 10 and 0.1ย ฮฉโm, respectively, the resulting computed water saturation of 50% will have a fractional uncertainty of 7%, which increases rapidly for porosities less than 10%. The uncertainty depends on the combination of reservoir parameters. At high porosity, the major contributor to uncertainty is formation resistivity. At intermediate porosity, the major contribution is from the cementation exponent. And, at low porosity, the most significant parameter is porosity itself. Archieโs work is one of many fine papers in the archives of SPE and the Society of Professional Well Log Analysts that deserve to be read, to understand the methods described therein, where they can be applied, and, possibly more importantly, where they cannot. Simply knowing how to drive expensive interpretation software is no substitute for a solid understanding of the fundamental theory behind the key strokes. Recommended additional reading at OnePetro: www.onepetro.org. SPE 158545 A Greater Dolphin Area Case Study Part 1: Defining Geological Uncertainty by K.S. Taylor, BG, et al. SPE 163973 Gas/Condensate Flow Behavior Within Tight Reservoirs by Mahmood Al-Harrasi, Petroleum Development Oman, et al. SPE 164884 Modeling Net-to-Gross in Deepwater Reservoirs by Jiajie Chen, Marathon, et al. IPTC 16808 The Eagle Ford Shale Play, South Texas: Regional Variations in Fluid Types, Hydrocarbon Production, and Reservoir Properties by Yao Tian, Texas A&M University, et al.
- Reservoir Description and Dynamics > Reservoir Characterization (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Open hole/cased hole log analysis (0.92)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Shale oil (0.56)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Shale gas (0.56)
Quantitative Formation Evaluation Toolkit for High-Angle and Horizontal Wells
Guo, Pingjun (ExxonMobil Production Co) | Zhou, Jinjuan (ExxonMobil Production Co) | Lewis, Daniel (ExxonMobil Production Co) | Mendoza, Alberto (Exxon Neftegas Co. Ltd) | Gaillot, Philippe (ExxonMobil Exploration Co.) | Wertanen, Scott (Mobil Cepu. Ltd) | Fitz, Dale (ExxonMobil Exploration Co.) | Passey, Quinn (ExxonMobil Upstream Research Co.)
Abstract Over the last decade, high angle and horizontal well drilling has played an important role in the development of many prolific oilfields in the world. The ability to optimally place wellbores within reservoirs leads to economic hydrocarbon production by providing greater penetration of oil columns above oil-water contacts as well as tapping into oil zones from remote locations. In this paper, we introduce a state-of-art formation evaluation toolkit specifically developed for quantitative interpretation of high angle and horizontal well logs. Starting with wellbore images and standard triple-combo field logs, the workflow consists of 1) a comprehensive image analysis module to build a 3D earth model; 2) a depth coherence analysis module to accurately align bed boundaries detected by a suite of logging tool sensors with different depths of investigation; 3) a 3D joint inversion module to model and interpret nuclear porosity and resistivity logs; 4) an output module in which a common earth model is populated with bedding geometries and rock and fluid property distributions. The advanced formation evaluation toolkit enables geoscientists to realize much more value than ever before from high angle and horizontal well logs. The detailed description of the internal architecture and lateral petrophysical characterization of the reservoirs are essential for understanding the stratigraphic structures and conditioning geological models. The improved estimations of the petrophysical properties yield more accurate estimates of reserves in place. Field examples of horizontal wells will be shown to demonstrate the uplift.
- North America > United States > Texas (1.00)
- Europe (1.00)
- Asia (0.93)
- Geophysics > Borehole Geophysics (1.00)
- Geophysics > Seismic Surveying > Borehole Seismic Surveying (0.66)
- North America > United States > Texas > East Texas Salt Basin > East Texas Field > Woodbine Formation (0.99)
- North America > Canada > Alberta > Duncan Field > Allied Siebens Tower 11-11-75-16 Well (0.94)
- North America > United States > Texas > Fort Worth Basin > Ellis Field (0.93)
- Well Drilling > Well Planning > Trajectory design (1.00)
- Well Drilling > Drilling Operations > Directional drilling (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Open hole/cased hole log analysis (1.00)
Abstract This paper presents the results of using a new workflow to correct and validate logging-while-drilling measurements (LWD) from horizontal wells, and the impact of the results in the petrophysical answers derived from the measurements. The workflow involves building a layered geological model and modeling the log responses in a model-compare-update loop to obtain the log properties of each layer. While similar methodology has been available in the past, the process was laborious and time consuming, and therefore it was not well applied in the industry. The paper demonstrates how the new process addresses the most common effects in horizontal wells in a timely and efficient manner, allowing it to form a part of petrophysical analysis in high angle and horizontal wells. In high angle and horizontal wells it is often difficult to apply the traditional petrophysical interpretation techniques normally used in vertical wells, due to geometric effects on the data in particular the resistivity logs. These effects include local layering or resistivity anisotropy, and boundary effects such as proximity and polarization horns on the resistivity measurements. Other effects complicating the borehole environment include asymmetric invasion profiles, the presence of cuttings beds and drilling mud segregation. This means that the data is challenging to interpret and the petrophysical answers from horizontal wells are not always fully used in static reservoir models. The inclusion of the corrected petrophysical properties from this processing into the static reservoir model reduces uncertainty and improves model accuracy. The workflow was applied on wells in a development field in North America. The reservoir consists of a few tens of feet thick silty sand and siltstone layers deposited in a shelfal environment. The extended reach wells used in the development of the field have long lateral sections (from 5,000 to 10,000 ft). Due to the geological complexity of the area, the wells often cross multiple layers and faults and are actively steered to optimize reservoir contact. The geological environment from static reservoir model was efficiently confirmed and refined, log responses corrected and verified before being used in the petrophysical analysis. The comparison of log responses between vertical and deviated wells was helpful both for quality control and in the well log modeling phase to assess the correct record of petrophysical properties for the input logs and for the modeling results. The update of the log measurements and resulting improvement in petrophysical answers is presented. The workflow requires strong integration between the Reservoir Geology, Drilling and Petrophysics teams. The paper presents a case study of the application of a new workflow to improve petrophysical answers from logging while drilling measurements in high angle and horizontal wells. The study demonstrates how log modeling in high angle and horizontal wells can be used to improve formation evaluation. The improved formation evaluation and updated geological model reduces uncertainty and adds detail.
- Geology > Geological Subdiscipline (0.94)
- Geology > Sedimentary Geology > Depositional Environment (0.94)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.30)