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Hill, A. D. (Texas A&M University) | Laprea-Bigott, M. (Texas A&M University) | Zhu, D. (Texas A&M University) | Moridis, G. (Texas A&M University) | Schechter, D. S. (Texas A&M University) | Datta-Gupta, A. (Texas A&M University) | Abedi, S. (Texas A&M University) | Correa, J. (Lawrence Berkeley National Laboratory) | Birkholzer, J. (Lawrence Berkeley National Laboratory) | Friefeld, B. M. (Class VI Solutions, Inc.) | Zoback, M. D. (Stanford University) | Rasouli, F. (Stanford University) | Cheng, F. (Rice University) | Ajo-Franklin, J. (Rice University / Lawrence Berkeley National Laboratory) | Renk, J. (Department of Energy) | Ogunsola, O. (Department of Energy) | Selvan, K. (INPEX Eagle Ford LLC)
The Eagle Ford Shale Laboratory is a DOE and industry-sponsored multi-disciplinary field experiment aimed at applying advanced diagnostic methods to map hydraulic fractures, proppant distribution, and the stimulated reservoir volume. The field site is an Inpex Eagle Ford, LLC lease in LaSalle county, Texas that has a legacy Eagle Ford producing well and that will be developed with 5 new producers. Utilizing newly-developed monitoring technologies, the project team will deliver unprecedented comprehensive high-quality field data to improve scientific knowledge of three important processes in unconventional oil production from shales: (1) a re-fracturing treatment in which the previously fractured legacy well will be re-stimulated for improved production, (2) a new stimulation stage where the most advanced hydraulic fracturing and geosteering technology will be applied during zipper-fracturing of 3 new producers, and (3) a Gas-Injection Enhanced Oil Recovery (EOR) Phase where one of the wells will be later tested for the efficiency of Huff and Puff gas injection as an EOR method. Field monitoring is being complemented with laboratory testing on cores and drill cuttings, and coupled modeling for design, prediction, calibration, optimization, and code validation. The multi-disciplinary team consists of researchers from Texas A&M University, Lawrence Berkeley National Laboratory, Stanford University, Rice University, and Inpex Eagle Ford, LLC.
The ultimate objective of the Eagle Ford Shale Laboratory Project is to help improve the effectiveness of shale oil production by providing new scientific knowledge and new monitoring technology for both initial stimulation/production as well as enhanced recovery via re-fracturing and EOR. The main scientific/technical objectives of the project are:
Build and test active seismic monitoring with fiber optics in an observation well to conduct: (1) real-time monitoring of fracture propagation and stimulated volume, and (2) 4D seismic monitoring of reservoir changes during initial production and during an EOR pilot.
Test distributed temperature sensing (DTS), distributed acoustic sensing (DAS) and distributed strain sensing (DSS) with fiber optic technology and develop protocols for field application.
Assess spatially and temporally resolved production characteristics and explore relationships with stimulated fracture characteristics by open hole logging, cased hole logging, production logging, and tracer technology.
Understand rock mechanical properties and reservoir fluid properties and their effect of stimulation efficiency through coring and core analysis.
Evaluate suitability of re-fracturing to achieve dramatic improvements in stimulated volume and per well resource recovery.
Develop understanding of gas-based EOR Huff and Puff methods to increase per well resource recovery by lab tests and field test.
Nailing, Xiu (Petrochina Research Institute of Petroleum exploration & Development) | Yun, Xu (Petrochina Research Institute of Petroleum exploration & Development) | Yuzhong, Yan (Petrochina Research Institute of Petroleum exploration & Development) | Xin, Wang (Petrochina Research Institute of Petroleum exploration & Development) | Tiancheng, Liang (Petrochina Research Institute of Petroleum exploration & Development) | Haifeng, Fu (Petrochina Research Institute of Petroleum exploration & Development) | Yongjun, Lu (Petrochina Research Institute of Petroleum exploration & Development)
ABSTRACT: In order to reveal the influence of horizontal bedding and high-angle natural fracture on vertical extension and geometry of hydraulic fractures in shale reservoir, and provide technical support for vertical depth optimization of horizontal Wells and fracturing technology selection of fracture vertically breakthrough bedding, we investigated the propagation of fractures with different methods. In a series of laboratory experiments, we investigated the influence of bedding on fracture extension and fracture geometry using large-scaled true triaxial hydraulic fracturing experimental system. We monitored the hydraulic fractures of horizontal wells in the shale gas demonstration area of sichuan basin of china using tiltmeters, and observed the influence of horizontal bedding and high-angle natural fracture on vertical extension and geometry of hydraulic fractures in shale reservoir. We compared the influence of different vertical distances between horizontal Wells and high-quality shale on production effect through production data analysis. The research results showed that horizontal bedding had apparent influence on fracture geometry, and the existence of the horizontal bedding made it easier for horizontal fracture propagation. The vertical depth optimization of horizontal Wells had a significant impact on the stimulation effect, and we found that the closer the horizontal Wells are to the high-quality shale, the easier it is to obtain a better production effect. The tiltmeter mapping results showed that the high- Angle natural fracture was the key geological factor for hydraulic fractures breaching horizontal beddings in shale reservoirs. The research results can be of guiding significance for optimizing the depth position of horizontal Wells and exploring the method in breaching the horizontal beddings in shale reservoir.
Horizontal wells provide the opportunity to initiate fracture networks and dramatically increase the connection between the wellbore and the shale gas reservoir[1-3]. This has allowed the economic development of shale gas reservoir that cannot be pursued without reservoir stimulation[4-5]. But this does not imply that the shale gas reservoirs are adequately stimulated. Recent field results in the Shale gas demonstration area in sichuan basin of China are yielding many questions to us, including
⋆ Are vertical height growth of hydraulic fractures sufficient?
⋆ Whether the horizontal beddings restrict the vertical extension of hydraulic fractures?
⋆ Whether the vertical distance from horizontal well to the high quality shale intended zone affects production?
Zhang, Yuanyin (Petroleum Exploration and Production Research Institute, Sinopec) | Jin, Zhijun (Petroleum Exploration and Production Research Institute, Sinopec) | Chen, Yequan (Petroleum Exploration and Production Research Institute, Sinopec) | Liu, Xiwu (Petroleum Exploration and Production Research Institute, Sinopec)
Density is substantially significant for the prediction of shale reservoir quality in China. The actual pre-stack density inversion problems are typically ill-posed because: 1) real data are discrete and contaminated with noise, 2) most AVO equations are derived under many assumptions or approximations, and 3) the nonuniqueness of the inverse problem causes many models to fit the data. Conventional regularization through directly using the good robustness of P-impedance inversion is unacceptable for density enhancement in the shale reservoirs, since shale reservoir’s radioactivity and acoustic properties are often not correlative. In this paper, based on the basic theories of AVO inversion and Bayesian, we employ the pseudo-P-impedance (FIp) constructed from P-impedance and Uranium (U) logging curves to formulate the density inversion in the shale reservoirs. In particular, the non-regularized, traditional-regularized and the proposed-regularized inversion methods are respectively compared by using both numerical and field data. It is found that the proposed inversion method shows strong anti-noise ability and robustness. And it is more beneficial for achieving better density results for shale reservoirs.
Presentation Date: Wednesday, September 27, 2017
Start Time: 3:30 PM
Presentation Type: ORAL
Sam Zandong Sun, Sam Zandong (China University of Petroleum) | Sun, Yongyang (China University of Petroleum) | Liu, Zhishui (China University of Petroleum) | Dong, Ning (Institute of Exploration and development, SINOPEC) | Liu, Junzhou (Institute of Exploration and development, SINOPEC) | Xia, Hongming (Institute of Exploration and development, SINOPEC)
Kerogen is not only regarded as a significant indicator for gas source potential, but also seen as an important composition embedded in shale matrix or filled in pore space. Meanwhile, there are also some microcracks existing in kerogen according to SEM observations published previously which are usually ignored. Aimed at multiple pore types developed in Jiannan area, this paper proposes a dual rock physics model with complicated pore types for organic-rich shale. Pore space is divided into two parts – matrix porosity and kerogen porosity. Kerogen pore space is full filled with oil or gas. In addition, matrix pore space is also split into moldic pores, inter-particle pores and cracks. Based on the above analysis, wide discussion about the effects of kerogen on elastic properties of shale is made to provide a guidance for the optimization of interval for fractured. Application on two shale wells from Southern China agrees well with gas detection and practical production, which proves its feasibility and effectiveness.
China has seen its natural gas consumption rise significantly over recent years. As a result, unconventional energy, specifically shale gas, has become a focused alternative. However, major challenges to develop efficient shale gas extraction, such as the geology, undulating terrain, lack of water resources, immature expertise prevail. Thus, large scale commercial production of shale gas remains in its infancy.
The Sichuan basin is a testament of this where exploration and production of unconventional reservoirs have taken place since the 1950s. With the basin resting in a major compressional tectonic area, part of the shale gas reservoirs is fractured, sensitive to abrupt structural dip changes and faulted standoffs. This complicates reservoir stimulation with unpredictable fracture orientations and growth. Lateral property changes within the reservoir and varying stratigraphic thickness adds to this shortcoming.
To shorten the learning curve, successful and established workflows from US plays such as the Eagle Ford, Marcellus and Barnett were introduced. From these plays, it was established that different shale plays retains distinct differences that were addressed through customization in the process and workflows. The differences were identified through detailed evaluations of reservoir quality(RQ) and completion quality(CQ). However, to address the local challenges during well construction, a new focus is needed with the introduction of drilling quality (DQ).
In this aspect, PetroChina South West Oil and Gas Company (SWOGC) operating in one of the Sichuan shale plays adopted the above workflow to accumulate and analyze the data with the objective to establish the main drivers for reservoir production towards recovery enhancement. Consequently, the customization of process and workflows to support large scale commercial shale gas development in the Sichuan Basin can be achieved.
In conventional reservoirs, the correlation of reservoir quality (RQ) to production is a standard practice. RQ is defined as the product of various rock properties, including saturation (S), porosity (???), thickness (h) and, in some cases, permeability (k). Plotting RQ against normalized well production gives an indication of rock type and hence production trends.
To use this methodology in unconventional reservoirs, it is necessary to modify the relationship to account for the complexity and heterogeneous nature of shale rock. Modification of the method involves the identification of the most representative combination of rock properties used to calculate reservoir quality, which are then compared to multivariable, normalized cumulative production at different time intervals. Applying this relation in the Eagle Ford shale resulted in the observation of two trends, implying that different production trends were in play and should be further investigated.
This paper presents a detailed well-by-well study conducted in the Eagle Ford shale to define the rock characteristics that caused the presence of two production trends. History matches using numerical modeling and rate transient analysis were performed to verify whether two production trends were present. When available, borehole images can be used to validate and extrapolate this localized production analysis to a basin-level understanding.
The objective of this study was to determine a correlation between RQ parameters as obtained from well logs and production performance in the Eagle Ford shale. This led to the identification of different rock types, implying different production trends. This correlation technique has been used in the past for carbonates, sandstones (Pickett and Artus, 1970) and muddy sands (Aguilera, 1995) and is known as "petrophysics-to-production?? methodology. The original methodology correlates recoverable production from decline curves with an RQ index (a function of So, ???h and k) as depicted in the left plot in Figure 1a, which shows three different production trends. Pickett (1970) identified that each trend corresponds to a different rock type with a different production performance where the gentler trend is due to a non-fractured rock type (k/???)2. For this study, the original approach has been adapted as depicted in the right plot in Figure 1b by modifying the production term as cumulative production normalized to lateral length and the RQ index defined using a petrophysical model.
Lakatos, I. (Research Institute of Applied Chemistry, University of Miskalc, and Research Group of Earth Sciences,) | Lakatos-Szabo, J. (Research Institute of Applied Chemistry, University of Miskalc, and Research Group of Earth Sciences,)