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Collaborating Authors
Results
SUMMARY The ability of the marine controlled source electromagnetic method to resolve anisotropy in the sediment conductivity is not very well understood. In this study, we address the resolvability of anisotropy using a Bayesian approach. Two markedly different methods, slice sampling and reversible jump Markov Chain Monte Carlo have been used for the Bayesian inversion of a synthetic model of a resistive oil reservoir trapped beneath the seabed. We use this to identify which components of data can provide the strongest constraints on anisotropy in the overburden, reservoir and underlying sediments.
- Oceania > Australia > Western Australia > North West Shelf > Carnarvon Basin > Exmouth Plateau > WA-1-R > Scarborough Field (0.99)
- Africa > South Africa > Western Cape Province > Indian Ocean > Bredasdorp Basin > Block 9 > EM Field (0.99)
- Reservoir Description and Dynamics > Reservoir Simulation > History matching (0.72)
- Reservoir Description and Dynamics > Reservoir Simulation > Evaluation of uncertainties (0.72)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (0.56)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (0.49)
- Information Technology > Artificial Intelligence > Machine Learning > Statistical Learning (0.55)
- Information Technology > Artificial Intelligence > Representation & Reasoning > Uncertainty > Bayesian Inference (0.34)
- Information Technology > Artificial Intelligence > Machine Learning > Learning Graphical Models > Directed Networks > Bayesian Learning (0.34)
Developing a Predictor for Degradation of High Strength Corrodible Tripping Balls used in Multi-Zone Fracturing Treatments in Unconventional Hydrocarbon Reservoirs
Carrejo, Nick (Baker Hughes Inc.) | Mathur, Vipul (Baker Hughes Inc.) | Mazyar, Oleg A. (Baker Hughes Inc.) | Gaudette, Sean (Baker Hughes Inc.)
Abstract Multi-point hydraulic fracturing in unconventional hydrocarbon-bearing shale reservoirs has proven to greatly enhance production economics. Recent technology has allowed for as many as 40 individual fracture points. Tripping balls are a major component of these multi-point fracturing systems and are used to actuate fracturing sleeves to pinpoint fracture initiation and placement. While seated on ball seats, the tripping balls may experience pressures approaching 10,000psi. However, following a successful formation fracture, the tripping balls may hinder production. Potential problems relate to the tripping balls becoming stuck on the fracturing seats. Tripping balls remaining in the lateral can also lead to problems if wellbore re-entry is required. These production risks can lead to significantly increased costs and potential lost production. A new, high-strength corrodible material has been developed for tripping balls to alleviate potential problems in these unconventional reservoirs. This material has yielded an interventionless means of flow assurance. The mechanical properties and degradation rates of these newly engineered materials have been investigated to determine the downhole characteristics. The characterization results of these materials are discussed in an effort to develop a method for accurately predicting the timeframe in which these high-strength corrodible tripping balls fully degrade, and thus eliminate possible production risks. The testing included investigations of the degradation rates of these materials in brines, and at various temperatures. Materials were also pressure tested on multiple ball seat configurations used in the multi-zone fracturing systems1.
- North America > Mexico (0.28)
- North America > Canada (0.28)
Abstract Fracture fluid flow back has been identified as one of the major challenges of hydraulic fracturing operations conducted in shale reservoirs. Factors causing the very low fracture fluid recovery need to be well understood and properly addressed, in order to get full benefits from costly hydraulic fracture jobs conducted in unconventional reservoirs. Despite the recent surge of investigations of the problem, one major question still remains: what happens to the fracture fluid that is not recovered? Does it stay in the fracture or does it go into the matrix? In case of both mechanisms are responsible for fracture fluid retainment, what fraction of fracture fluid stays in the propped fracture and what fraction is transferred from fracture to matrix. The focus of the current study is to understand if the transfer of fracture fluid from fracture to matrix through imbibition is of significant importance. We systematically measure the imbibition rate of water, brine, and oil into the actual core samples from the three shale sections of Horn River basin (i.e., Fort Simpson, Muskwa and Otter Park). We characterize the shale samples by measuring, porosity, wettability, mineral composition through XRD analysis, and interpreting the well log data. The results show that imbibition could be a viable mechanism for fluid transfer from fracture to matrix in Horn River shales. The comparative study shows the imbibition rate in the direction parallel to the bedding plane is higher than that in the direction perpendicular to the bedding. The study also suggests that the imbibition rate of the aqueous phases is significantly higher than that of the oleic phases.
- North America > Canada > British Columbia (1.00)
- North America > Canada > Northwest Territories > Fort Simpson (0.29)
- Research Report > New Finding (1.00)
- Research Report > Experimental Study (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (1.00)
- Geology > Mineral (1.00)
- Well Completion > Hydraulic Fracturing (1.00)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Shale gas (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
- (3 more...)
Marine CSEM of the Scarborough gas field, Part 1: Experimental design and data uncertainty
Myer, David (University of California at San Diego, BlueGreen Geophysics, LLC) | Constable, Steven (University of California at San Diego) | Key, Kerry (University of California at San Diego) | Glinsky, Michael E. (CSIRO Earth Science and Resource Engineering, University of Western Australia) | Liu, Guimin (BHP Billiton)
ABSTRACT We describe the planning, processing, and uncertainty analysis for a marine CSEM survey of the Scarborough gas field off the northwest coast of Australia, consisting of 20 transmitter tow lines and 144 deployments positioned along a dense 2D profile and a complex 3D grid. The purpose of this survey was to collect a high-quality data set over a known hydrocarbon prospect and use it to further the development of CSEM as a hydrocarbon mapping tool. Recent improvements in navigation and processing techniques yielded high-quality frequency domain data. Data pseudosections exhibit a significant anomaly that is laterally confined within the known reservoir location. Perturbation analysis of the uncertainties in the transmitter parameters yielded predicted uncertainties in amplitude and phase of just a few percent at close ranges. These uncertainties may, however, be underestimated. We introduce a method for more accurately deriving uncertainties using a line of receivers towed twice in opposite directions. Comparing the residuals for each line yields a Gaussian distribution directly related to the aggregate uncertainty of the transmitter parameters. Constraints on systematic error in the transmitter antenna dip and inline range can be calculated by perturbation analysis. Uncertainties are not equal in amplitude and phase, suggesting that inversion of these data would be better suited in these components rather than in real and imaginary components. One-dimensional inversion showed that the reservoir and a confounding resistive layer above it cannot be separately resolved even when the roughness constraint is modified to allow for jumps in resistivity and prejudices are provided, indicating that this level of detail is beyond the single-site CSEM data. Further, when range-dependent error bars are used, the resolution decreases at a shallower depth than when a fixed-error level is used.
- Overview (0.66)
- Research Report (0.40)
- Oceania > New Zealand > South Pacific Ocean > Lau Basin (0.99)
- Oceania > Fiji > South Pacific Ocean > Lau Basin (0.99)
- Oceania > Australia > Western Australia > North West Shelf > Carnarvon Basin > Exmouth Plateau > WA-1-R > Scarborough Field (0.99)
- (2 more...)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
- Data Science & Engineering Analytics > Information Management and Systems (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Geologic modeling (0.93)
ABSTRACT In this article, the Editor of provides an overview of all technical articles in this issue of the journal.
- Geophysics > Seismic Surveying > Seismic Processing (1.00)
- Geophysics > Seismic Surveying > Seismic Modeling > Velocity Modeling (1.00)
- Geophysics > Electromagnetic Surveying (1.00)
- Geophysics > Borehole Geophysics (1.00)
- Oceania > Australia > Western Australia > North West Shelf > Carnarvon Basin > Exmouth Plateau > WA-1-R > Scarborough Field (0.99)
- North America > Canada > Saskatchewan > Williston Basin > Weyburn Field > Mission Canyon Formation (0.99)
- North America > Canada > Saskatchewan > Williston Basin > Weyburn Field > Madison Formation (0.99)
- (3 more...)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
- Data Science & Engineering Analytics > Information Management and Systems > Artificial intelligence (1.00)
Abstract The giant Wafra Field is the largest field in the Partition Zone (PZ) between Saudi Arabia and Kuwait. The Cretaceous Wara reservoir represents one of the most prolific producing zones in the PZ. The Wara is a Cretaceous sequence of channel sands (fluvial/tidal) that have locally complex vertical and a stacking patterns. These sands are interpreted to have been deposited in a tidally influenced lower delta plain depositional environment in a low angle ramp setting characterized by low accommodation space. Stratigraphic complexity is high and in general, sandstone bodies are below seismic resolution. The Wafra Wara reservoir is a structural accumulation formed by a low amplitude anticline with 4-way dip closure, with some structural complexity at the reservoir level, consisting of normal faults with small displacements. Although the Wafra Wara clastic reservoir is mature, new "sweet spots" with original formation pressure were drilled recently in the middle of the development area, and there is also still significant remaining oil on the current margins of the field where deeper OWCs have recently been encountered. Increasing water cut and an active aquifer present some challenges to maintaining good oil production in the reservoir, mitigated by production optimization efforts and a rigorous surveillance program. A comprehensive multidisciplinary study was performed to identify new infill well and workover opportunities within the most mature portion of the field to increase production and recovery. The team reviewed all existing data and performed detailed 3D-seismic interpretation to refine stratigraphy and structure, generate production attribute maps and to understand the production history and current state of the reservoir. Production, well-test data, cased-hole logs and analytical techniques were used to identify areas with by-passed oil and to predict initial rates and incremental recovery for infill wells. Deterministic and probabilistic forecasts were generated using field and offset well decline curve analysis. New opportunities were then ranked based on geological and engineering criteria. This paper highlights the challenges and lessons learned from this integrated reservoir management study to define remaining oil and to identify opportunities to increase ultimate recovery.
- Geology > Structural Geology (1.00)
- Geology > Geological Subdiscipline > Stratigraphy (1.00)
- Geology > Sedimentary Geology > Depositional Environment > Continental Environment > Fluvial Environment (0.48)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.36)
- Asia > Middle East > Saudi Arabia > Saudi Arabia - Kuwait Neutral Zone ("Partitioned Zone") > Arabian Basin > Widyan Basin > Wafra Joint Operations Block > Wafra Field (0.99)
- Asia > Middle East > Kuwait > Saudi Arabia - Kuwait Neutral Zone ("Partitioned Zone") > Arabian Basin > Widyan Basin > Wafra Joint Operations Block > Wafra Field (0.99)
- Asia > Middle East > Kuwait > Ahmadi Governorate > Arabian Basin > Widyan Basin > Wara Formation (0.99)
- (13 more...)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
- Reservoir Description and Dynamics > Reserves Evaluation (1.00)
- (4 more...)
Abstract Several wells have been drilled in the south eastern side of Tunisia but only two wells are producing. However, to better understand the petroleum system mechanism of the area, a geochemical study was performed including oil-oil and oil-source rock correlation that was proved to be an essential tool for assessing oils occurrence, source rocks characteristics, their depositional environments and their distributions. The geochemical study was followed by 1D basin modeling to better understand the petroleum system functioning of the area. The geochemical survey is based on the analysis of a total of 214 cutting samples and 6 crude oil samples. In a first part, potential Silurian and Ordovician source rocks were analyzed by Rock Eval to characterize their petroleum potential. In the second part, DST oil samples are correlated to Silurian and Ordovician source rocks using biomarkers and light hydrocarbon fraction. Migration distances calculation was based on carbozoles and benzocarbozoles. Rock Eval results show that Silurian Hot shales exhibit good petroleum potential with mature type II oil prone kerogen, while Ordovician Shales show poor to fair petroleum potential and contain bad preserved type II kerogen. Geochemical correlations study proved that the Silurian Hot shales are the main source rock in the basin and excluded any contribution from the Ordovician shales. Carbozoles and benzocarbozoles concentrations in the oils of the northern part of the area suggest close proximity to the source kitchen while oils from the southern part seem to be sourced by a kitchen located in Ghadames basin. The 1D modeling indicates that oil and gas generation from the Silurian hot shales began in the Carboniferous at about 360 Ma and reaches the maximum generation phase in the Upper Jurassic at about 160 Ma. The Hercynian unconformity surface was the main drain of secondary migration in the basin.
- Phanerozoic > Paleozoic > Silurian (1.00)
- Phanerozoic > Paleozoic > Ordovician (1.00)
- Phanerozoic > Mesozoic > Jurassic > Upper Jurassic (0.34)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (1.00)
- Geology > Geological Subdiscipline > Geochemistry (1.00)
- Geology > Geological Subdiscipline > Economic Geology > Petroleum Geology (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (0.48)
- South America > Brazil > Brazil > South Atlantic Ocean > Santos Basin (0.99)
- Oceania > Australia > Western Australia > North West Shelf > Carnarvon Basin > Dampier Basin > WA-209-P > Oryx Field > Oryx 1 Well (0.99)
- North America > United States > California > San Joaquin Basin (0.99)
- (11 more...)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
- Reservoir Description and Dynamics > Fluid Characterization > Geochemical characterization (1.00)
Abstract Presently shale reservoirs are the one of the hottest plays in the oil industry. Our understanding of these reservoirs rapidly progressed from one of a continuous type, to that of a spatially varying type. Two key elastic parameters, Young’s modulus and Poisson’s ratio are critically relied upon, to seismically high-grade these spatially varying reservoirs in terms of their reservoir and completion qualities. Isotropic elastic properties are assumed in the delineation of ‘frac’able’ zones and sweet spots. However, these shale formations are highly anisotropic even in the absence of any in-situ fractures and there are multiple Young’s moduli and Poisson’s ratios in an anisotropic medium. In this paper we discuss the effects of vertical transverse isotropy (VTI) in characterizing shale reservoirs in terms of Young’s moduli and Poisson’s ratios. We begin by rewriting Young’s modulus and Poisson’s ratio formulae in terms of Thomsen’s anisotropy parameters (Thomsen,1986). Both approximate and exact expressions are given. Approximate relations in terms of anisotropy parameters are easier to interpret than those in terms of the stiffness coefficients. We then discuss the results in terms of relevant ranges of values of these anisotropy parameters. Also, an important contribution to fracture initiation and containment comes from the uniaxial stress ratio (Higgins et al., 2008;Sayers, 2010, Iverson, 1995). It is the ratio of the horizontal to the vertical stresses in the absence of any transverse strain. The effects of anisotropy on the uniaxial stress ratio are discussed in this context. Finally we discuss how P-wave surface seismic data can be integrated with borehole and other measurements to estimate relevant elastic attributes in these highly anisotropic shale formations.
- North America > United States > Texas (0.30)
- North America > Canada > Alberta (0.29)
- Europe > Norway > Norwegian Sea (0.25)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (1.00)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geophysics > Seismic Surveying > Passive Seismic Surveying > Microseismic Surveying (0.94)
- Geophysics > Seismic Surveying > Borehole Seismic Surveying (0.94)
- Geophysics > Seismic Surveying > Seismic Modeling > Velocity Modeling > Seismic Inversion (0.46)
- Geophysics > Seismic Surveying > Seismic Modeling > Velocity Modeling > Seismic Anisotropy (0.34)
- North America > United States > South Dakota > Williston Basin (0.99)
- North America > United States > North Dakota > Williston Basin (0.99)
- North America > United States > Montana > Williston Basin (0.99)
- (11 more...)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Shale gas (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Reservoir geomechanics (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)