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Results
A Pilot Demonstration of Flaring Gas Recovery During Shale Gas Well Completion in China
Xue, Ming (CNPC Research Institute of Safety and Environmental Technology) | Li, Xingchun (CNPC Research Institute of Safety and Environmental Technology) | Cui, Xiangyu (CNPC Research Institute of Safety and Environmental Technology) | Wang, Qi (CNPC Research Institute of Safety and Environmental Technology) | Liu, Shuangxing (CNPC Research Institute of Safety and Environmental Technology) | Zheng, Jiale (CNPC Research Institute of Safety and Environmental Technology) | Wang, Yilin (CNPC Research Institute of Safety and Environmental Technology)
Abstract Objectives/Scope As one of the largest emitters in the world, the oil and gas industry needs more efforts on greenhouse gas reduction. Methane, as a potent greenhouse gas, could largely determine whether natural gas could serve as a bridging energy towards a sustainable future. In the past decade, the oil and gas companies in China has significantly enhanced casing gas recovery and reduced large volume of flaring (>20k m/day). However, the remaining low- to mid- volume flaring gas were left for further recovery. Methods, Procedures, Process Shale gas production in China has met a surge in the number of drilling wells. Those new wells were characterized by a relatively low gas production rate (<1 mill m/day), in comparison with the shale gas well in the US. As a result, flaring gas during well completion needs to be recycled or used so as to enhance the gas recovery rate. In this study, a pilot demonstration project of flaring gas recovery was carried out to reduce greenhouse gas emission in Weiyuan shale gas region in Sichuan province, China. The technical route of dehydration and natural gas compression was adopted. The recycled natural gas was transformed into compressed natural gas (CNG) and transported to the nearest CNG station for further use. Results, Observations, Conclusions The inlet gas pressure were between 2.85 to 5.82 MPa and the outlet pressure were kept stable around 20 MPa to meet the standard of CNG. The minimum dew point temperature was -65.5 °C and the outlet temperature rise remained below 23 °C. The manufactured device also showed a sound flexibility with recover rate between 523.22 to 1224.38 m/h, which was the 28% to 157% of the designed capacity. An overall of 21k of natural gas was recoverd. Novel/Additive Information For a single well completion event, a total of 50k of natural gas could be recovered by this device. The device applied in the pilot demonstration has well matched with the local transportation, gas composition, and surface engineering of the well completion and has the potential of popularization and application in the shale gas region in Sichuan. In that case, it could reach a future economic return over 0.6 billion RMB.
- North America > United States (1.00)
- Asia > China > Sichuan Province (0.34)
- Energy > Oil & Gas > Upstream (1.00)
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (0.69)
Summary The ever-growing demand for energy, relatively high price of hydrocarbons, and recent advances in production technologies have brought tight hydrocarbon-bearing reservoirs into attention as a potential source of energy. However, the displacement physics at nano and micro scales and their impact on fluid flow in these rocks is poorly understood. The unconventional rocks, such as shale rocks, are highly heterogeneous, fine-grained, and their representative elementary volume is uncertain. In order to identify flow pathways in the pore network of these rocks, it is essential to characterize nanopores and their connectivity. This can be achieved using high-resolution 3D imaging technique provided by Focused Ion Beam milling and Scanning Electron Microscopy (FIB-SEM). In this technique, a sequence of 2D cross sectional images, spaced evenly through a region of bulk specimen, is acquired. The stack of 2D images is then re-constructed into a 3D digital gray-scale representation of the sample volume. In this study, a reservoir rock sample from a major shale oil reservoir is selected for high-resolution imaging and statistical analysis. Rock specimens, 1 to 2 cm in dimensions, are cut from different locations of the reservoir core from which a high-resolution 2D map and multiple 3D FIB-SEM images are obtained. The digital images are then visualized, segmented, and analyzed to obtain porosity, pore size distribution, pore aspect ratios, spatial distribution of organic/total porosity, and total organic content. We find that the majority of the pores are below 100 nm in radius for this rock. In addition, the total visible porosity and total organic content are in the range of 1 to 2% and 8 to 14 vol.%, respectively. Chemical composition and mineralogy of the samples are also evaluated by Energy Dispersive X-Ray Spectroscopy (EDS) analysis. Furthermore, 3D pore networks are extracted from the FIB-SEM images; pore connectivities are examined; and permeabilies are calculated by solving the Stokes equation numerically using the finite volume method. It is observed that the pore connectivity for these rocks is poor, resulting in low permeabilities ranging from 1 to 6 μD. Finally, the impact of calculated parameters on fluid flow in unconventional rocks is discussed.
- Europe (0.94)
- North America > United States > Wyoming (0.28)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (1.00)
- Geology > Geological Subdiscipline (1.00)
- North America > United States > Texas > Fort Worth Basin > Barnett Shale Formation (0.99)
- Europe > United Kingdom > Kimmeridge Formation (0.99)
- North America > United States > Kentucky > Quality Field (0.93)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Shale oil (1.00)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Shale gas (1.00)
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Flow in porous media (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
ABSTRACT: Log models have been developed for the Bossier and Haynesville shales of East Texas and northwestern Louisiana to evaluate the hydrocarbon potential of these mudrock systems. This effort has targeted approximately 40 wells having conventional logging suites obtained during the past 35 years; sometimes sonic logs are not available. Comparisons of TOC computed using the Δ Log R method for the Haynesville Shale reveals substantial underestimation of TOC values measured from core samples. Geochemical and petrological analyses reveal that the Haynesville Shale contains important amounts of carbonate, in addition to kerogen, quartz and clay. As such it is not a ‘simple’ clay-rich shale that this term commonly implies. This paper addresses calculation of reliable TOC estimates from wire-line logs for a lithologically complex mudrock. Complex lithology, typical of the Haynesville and sometimes seen in the Bossier, consists of clay (illite with subordinate chlorite), quartz, calcite and kerogen with possible gas in limited pore space. This combination of variable mineral content and pore fluid affects responses of all logs and renders simple interpretative models ineffective. Three log models have been developed to calculate reservoir characteristics for these varied lithologies, named HAYNESVILLE, BOSSIER and SHALE. The first 2 of these models use an optimized multiple log solver; lithologic components of the HAYNESVILLE are silt-sized quartz/clay (55% quartz, 45% illite), calcite and kerogen, those of the BOSSIER are illite, quartz and kerogen. The chief interpretative model is HAYNESVILLE; when VOL_CALCITE < 0.075 the BOSSIER model is applied. A simple SHALE model is needed because some wells exhibit sub-caliper wellbore rugosity in the Bossier, which adversely affects the density log and renders its use inappropriate. Log model results indicate that substantially improved estimates of TOC can be computed for the Haynesville and that calculation of geologically reasonable lithology variations are possible.
- North America > United States > Louisiana (1.00)
- North America > United States > Texas > Travis County > Austin (0.28)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (1.00)
- Geology > Mineral > Silicate (1.00)
- North America > United States > Texas > Haynesville Shale Formation (0.99)
- North America > United States > Texas > Fort Worth Basin > Barnett Shale Formation (0.99)
- North America > United States > Texas > East Texas Salt Basin > Cotton Valley Group Formation > Cotton Valley Group Formation > Bossier Shale Formation (0.99)
- (10 more...)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Shale gas (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Geologic modeling (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Open hole/cased hole log analysis (1.00)
Abstract This paper describes a simple method to identify, prioritize, and evaluate restimulation candidates in the Antrim Shale of the Michigan Basin. This work is being performed as part of an ongoing field-based Gas Research Institute (GRI) project investigating the Antrim Shale. There are between 500 and 1,000 Antrim Shale wells which could be candidates for restimulation due to previous screenouts and/or flowback problems, when sand consolidation material was not used. However, all of these wells might not benefit from restimulation, due to either poor reservoir quality or because the wells are already effectively stimulated. Based on historical results, we estimate the increase in reserves from restimulation could be between 50 and 400 MMscf per well, which could add 50 to 200 Bscf in future reserves from the 500-1,000 candidate wells. We have developed a novel injection test unit and procedure to help operators identify the best restimulation candidates in a cost-effective manner and in a reasonable amount of time. The test is designed to determine if there is an effective hydraulic fracture connected to the wellbore. To our knowledge, a test of this nature has not been used before for specifically identifying restimulation candidates. To date, we have run 50 tests, and identified potential restimulation candidates from about 1/3 of the tests. Introduction The Antrim Shale play in the Michigan Basin has been very active in recent years with over 500 well completions in 1993 alone. However, the Antrim Shale boom is relatively new. As recently as 1988, the majority of the activity was concentrated in Otsego Co., Michigan. But, since 1988, producing Antrim wells increased from about 500 to over 3500 wells with completions in six counties (see Fig 1). Antrim gas production also increased dramatically, rising from about 10 Bsc/year in 1988 to over 90 Bsc/year in 1993. The Gas Research Institute (GRI), recognizing the potential of the Antrim for adding to long term gas reserves, is currently involved in a detailed research project designed to advance technology in the Antrim. Objectives of this field-based project include increasing the effectiveness of fracture stimulations, developing methods for screening restimulation candidates, identifying optimal recompletion candidates and procedures, and improving the understanding of Antrim reservoir. This paper focuses on methods for screening restimulation candidates. Background The Antrim Shale is a black, organic rich shale which is currently being produced from depths between 500 to 2,300 fL It consists of two primary completion intervals, the Norwood and Lachine, separated by the gray Paxton shale, as illustrated in Fig 2. The Norwood is commonly about 20 ft thick and the Lachine is 80 ft thick. Generally, both intervals are fracture stimulated separately with nitrogen foam and sand. P. 155^
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (1.00)
- Geology > Petroleum Play Type > Unconventional Play > Shale Play > Shale Gas Play (1.00)
- North America > United States > West Virginia > Appalachian Basin (0.99)
- North America > United States > Virginia > Appalachian Basin (0.99)
- North America > United States > Texas > Permian Basin > Yeso Formation (0.99)
- (35 more...)