Day 3 Wed, September 26, 2018最新文献

{"title":"Is API Enough for Gamma Ray Logs, or Do We Need More?","authors":"F. Inanc, A. Vogt","doi":"10.2118/191717-MS","DOIUrl":"https://doi.org/10.2118/191717-MS","url":null,"abstract":"\u0000 Gamma-ray logs are so widely used in the industry that they can easily be classified as \"commodity\" services provided by large and very small service companies. In addition, gamma-ray tools are designed and produced by many companies. The wireline and logging-while-drilling (LWD) variants of this equipment present a large variability of these tools, their types and services. Although the standardization effort through the \"API\" definition helped end the chaotic outlook in the gamma-ray log world, it did not do much to elevate gamma-ray logs from the qualitative world to the quantitative world. Frequent complaints are still expressed about wireline and LWD tools not agreeing, different size LWD tools measuring differently, and logs from different service companies providing different results.\u0000 The major issue with gamma-ray logs is that the \"API\" definition is valid only if the tool is run in a 4.89-in. borehole filled with fresh water. Although all gamma-ray tools are supposed to provide the same results for such a well, in the real world there is no single one-size-fits-all concept. The measurements provided by tools characterized with the University of Houston (UH) GR pit standard will stray from a reading that can be relied on to be quantitatively correct. Although this is a well-known fact and there are environmental corrections available, no standard has been defined on how to develop the corrections. Service companies have their own internal correction approaches, resulting in a large variability from company to company. The gamma-ray logs obtained from different service companies are likely to differ from each other, even though they are corrected with their own correction algorithms.\u0000 The gold standard in LWD gamma-ray logging is the agreement between LWD gamma-ray logs and wireline logs. However, under what conditions they should agree with each other is far from clear. Can one expect a 6¾-in. LWD tool to deliver comparable logs to a wireline tool when both are run in 8½-in. holes with heavy mud? There should be clear-cut definitions of the conditions under which gamma-ray logs are compared to each other to qualify the agreement between the LWD and wireline gamma-ray tools.\u0000 In this paper we discuss the characterization process of the gamma-ray tools and how they behave in boreholes different than the UH GR characterization pit. Following that, we outline the proposals for developing gamma-ray correction strategies so that gamma-ray logs become quantitative logs rather than the qualitative logs of the past. This approach provides a second-level characterization of gamma-ray logs after the \"API\" standardization and provides insight for petrophysicists to understand the differences between the logs from different sources and to bring those logs together in a quantitative manner.","PeriodicalId":441169,"journal":{"name":"Day 3 Wed, September 26, 2018","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124653305","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Superior Transport Capabilities of Neutrally Buoyant Proppants in Slickwater Fluids Deliver Step-Change Increase in the Conductive Fracture Area of Unconventional Wells","authors":"H. Brannon","doi":"10.2118/191461-ms","DOIUrl":"https://doi.org/10.2118/191461-ms","url":null,"abstract":"\u0000 Technological advancements have recently been directed toward development and optimization of horizontal completions in unconventional reservoirs, with the ultimate objective of increasing asset performance and value. Unconventional plays are being completed with ever-longer laterals, tighter stage spacing, and high rate slickwater applications designed with increasingly larger volumes of sand to create increased reservoir contact area for greater hydrocarbon recovery. Success is predicated upon overcoming the limited transport capabilities of slickwater. The benefit of higher injection rates employed to enhance proppant transport is soon lost as the lateral velocity declines exponentially with distance from the wellbore, allowing the sand to fall rapidly to the bottom of fractures, resulting in propping only a fraction of the created fracture area. While there are advantages to the use of slickwater and sand for unconventional applications, the transport characteristics inherent to slickwater/sand slurries suggest significant limitations to step-changes in hydrocarbon recovery.\u0000 Near-neutrally buoyant, ultra-lightweight proppant is a proven solution to make productive the otherwise non-propped area. Several previous studies in parallel plate slot flow models have shown ULWP-1.05 is transported well in slickwater, whereas sand settles rapidly to form a dune even at high flow rates. Such behavior is intuitive given the near-neutrally buoyant ULWP has an Apparent Specific Gravity of 1.05, in contrast to the 2.65 ASG of sand and the 1.0 ASG of water.\u0000 Two new proppant transport models have recently been introduced, including a slot with multiple fracture branches and, a 3D complex network flow model designed to imitate flow through a lateral wellbore into a complex fracture network. In both, the ULWP-1.05 was observed to be transported near-homogeneously with the fluid to the extremities of the apparatus. Conversely, small mesh sand tended to stay in the lower sections of the models and to deposit prior to reaching the extremities.\u0000 As a prelude to ULWP-1.05 field application in Permian Basin extended length horizontal wells, proppant transport and fracture conductivity data for the near-neutrally buoyant ULWP-1.05 were used in fracture models to optimize proppant placement for maximizing conductive fracture area, with iterations to optimize well performance in production simulations. A desired outcome of this endeavor is the development and validation of an optimized stimulation design exhibiting materially enhanced well performance.\u0000 This paper includes analyses and observations from the proppant transport testing, fracture conductivity testing, discussion of the subsequent fracture designs and production simulations, and comparison of the production simulations with production experienced in field applications. Performance of slickwater fracs with sand alone and, with both sand and near neutrally buoyant ULWP are compared. Lessons learned may b","PeriodicalId":441169,"journal":{"name":"Day 3 Wed, September 26, 2018","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114545839","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Efficient Simulation of Two-Phase Compositional Flow in Fractured Reservoirs Using 3D Unstructured Gridding in Complex Geometries","authors":"A. Zidane, A. Firoozabadi","doi":"10.2118/191405-MS","DOIUrl":"https://doi.org/10.2118/191405-MS","url":null,"abstract":"\u0000 We present a higher-order numerical model for compositional two-phase flow in fractured media in 2D and in 3D unstructured gridding. The model accommodates all types of finite elements; in particular, quadrangular and triangular elements in 2D, and hexahedra, prisms and tetrahedra elements in 3D.\u0000 We apply for the first time the fracture cross-flow equilibrium (FCFE) concept in compositional two-phase flow in 3D. FCFE is combined with the hybridized form of the mass conservative mixed finite element (MFE) and the higher-order discontinuous Galerkin (DG) method. We have developed an interface that connects computer-aided-design (CAD) software to the mesh generator. The interface enables us to generate the most complicated fracture shapes. The application is intended for fracking simulation. To the best of our knowledge the complexity of fractures that we generate/simulate is not reported in the past. Our algorithm allows flow simulation in fractures in all range of permeability values as opposed to other models where low permeable fractures affect the accuracy of the results. We demonstrate the efficiency, accuracy, and strengths of our model in comparison to alternatives including the embedded discrete fracture approach in different examples. This work covers generation and simulation of two-phase compositional flow in complex fractured media in 3D unstructured gridding.","PeriodicalId":441169,"journal":{"name":"Day 3 Wed, September 26, 2018","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126836641","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Domain Decomposition Approach for Local Mesh Refinement in Space and Time","authors":"Gurpreet Singh, M. Wheeler","doi":"10.2118/191703-MS","DOIUrl":"https://doi.org/10.2118/191703-MS","url":null,"abstract":"\u0000 Reservoir simulations for complex multiphase flow and transport problems often suffer from non-linear solver convergence issues. These manifest in the form of restrictively small time-step sizes even while using unconditionally stable fully implicit schemes. These problems are further compounded when a local mesh refinement is used to accurately represent reservoir parameters available such as permeability, porosity, etc., at multiple spatial scales. We discuss a domain decomposition approach that allows different time-step sizes and mesh refinements in different subdomains (Singh and Wheeler (2018)) of the reservoir that circumvents these issues without compromising computational efficiency and prediction accuracy. This approach extends the well-known methodology of local mesh refinement in space (Wheeler et al. (2002)) to time. Our numerical experiments indicate that non-linear solvers fail to converge, to the desired tolerance, due to large non-linear residuals in a smaller subdomain. We exploit this feature to identify subdomains where smaller time-step sizes are necessary while using large time-step sizes in the rest of the reservoir domain. The three key components of our approach are: (1) a space-time, enhanced velocity, domain decomposition approach that allows different mesh refinements and time-step sizes in different subdomains while preserving local mass conservation, (2) a residual based error estimator to identify or mark regions (or subdomains) that pose non-linear convergence issues, and (3) a fully coupled monolithic solver is also presented that solves the coarse and fine subdomain problems, both in space and time, simultaneously. This solution scheme is fully implicit and is therefore unconditionally stable. The results indicate that using large time-step sizes for the entire reservoir domain poses serious non-linear solver convergence issues. Although using a smaller time step size for the entire domain reduces the convergence issues, it also results in substantial computational overheads. The proposed space-time domain decomposition approach, with smaller time-step sizes in a subdomain and large time-step sizes everywhere else, circumvents the non-linear convergence issue without adding computational costs. Additionally, a space-time monolithic solver renders a massively parallel, time concurrent framework for solving flow and transport problems in subsurface porous media. Since the proposed approach is similar to the widely used finite difference scheme, it can be easily integrated in any existing legacy reservoir simulator.","PeriodicalId":441169,"journal":{"name":"Day 3 Wed, September 26, 2018","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122119886","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Wastewater Injection and Slip Triggering: Results from a 3d Coupled Reservoir/Rate-and-State Model","authors":"Mohsen Babazadeh, J. Olson","doi":"10.2118/191670-MS","DOIUrl":"https://doi.org/10.2118/191670-MS","url":null,"abstract":"\u0000 This paper present results from a combined model that brings together injection physics, reservoir dynamics, and fault physics to better explain the primary controls on induced seismicity. We created a 3D fluid flow simulator with embedded discrete fracture technique, coupled with a 3D displacement discontinuity geomechanics model that uses rate and state friction to model stable or unstable rupture events. The model incorporates reservoir properties including vertical and horizontal extent; stratification including top-seal, reservoir, and basement; multiple permeability and porosity. Injection parameters include rate and pressure. Fault properties include size, 2D permeability, and frictional properties. Several suites of simulations were run to evaluate the relative importance of each of the factors from all three parameter groups.\u0000 We find that the injection parameters interact with the reservoir parameters in the context of the fault physics. For a given reservoir and fault properties, injection rate increases magnitude and frequency of earthquakes, and volume is unimportant. For a different reservoir, these relations may change, leading to the need to specify/examine the injection parameters only within the context of a particular faulted reservoir. Both injection and reservoir properties can interact with the fault properties to trigger or impede slip, so that the magnitudes of induced earthquakes depend on all three groups of parameters. For example, the fault permeability structure is a key factor in inducing earthquakes in basement in many reservoir scenarios. In some cases, the main component in inducing seismicity include the pressure on the fault and its rate of change, which affect how big of a fault area is being affected, and therefore initial earthquake size. By implication, selecting reservoirs for wastewater disposal may involve prioritizing those reservoirs with higher permeability as it takes longer for fluid pressure to exceed critical pressure and trigger large unstable rupture events on nearby faults.","PeriodicalId":441169,"journal":{"name":"Day 3 Wed, September 26, 2018","volume":"181 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133587429","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Aquifer Monitoring Technology for Safe Shale Oil and Gas Exploration and Extraction","authors":"Amina Boughrara Salman, Yoann Lage, A. Tuxen, P. L. Pedersen, Casper Laur Byg, M. Frederiksen, Jacob Ask Hansen, J. Hone, A. Law, S. Soua","doi":"10.2118/191678-MS","DOIUrl":"https://doi.org/10.2118/191678-MS","url":null,"abstract":"\u0000 Analysis of dissolved methane and volatile organic compounds (VOCs) in water is crucial in monitoring the underground water quality, specific to shale oil and gas subsurface activities. Existing methods for monitoring these analytes generally rely on manual sampling at hydrogeological boreholes followed by off-line chromatography-based laboratory analysis. These methods are labor intensive and prone to errors. In addition, they do not capture the dynamic variations, which are particularly interesting in the occurrence of methane. In this work, a new sensor-based instrumentation for in-situ detection and measurement of methane and VOCs in subsurface environments is presented. The methane detection method relies on the Non-Dispersive Infrared technology whereas VOCs are detected using the principle of photoionization detection.\u0000 It is demonstrated that the system has a relatively short response time combined with low detection limits for methane and VOCs. This makes the system suitable for monitoring aquifers in shale gas exploration sites with a fairly high temporal resolution thus giving information on dynamic variations in the methane and VOC concentrations.","PeriodicalId":441169,"journal":{"name":"Day 3 Wed, September 26, 2018","volume":"83 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127600627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}