Miscible injection is a proven, economically viable process that significantly increases oil recovery from many different types of reservoirs. Most miscible flooding projects use CO2 or nitrogen as solvents to increase oil recovery, but other injectants are sometimes used. This page provides an overview of the fundamental concepts of miscible displacement. Also provided are links to additional pages about designing a miscible flood, predicting the benefits of miscible injection, and a summary of field applications. Fieldwide projects have been implemented in fields around the world, with most of these projects being onshore North American fields.
Xia, Yang (China University of Petroleum, Beijing) | Jin, Yan (China University of Petroleum, Beijing) | Chen, Mian (China University of Petroleum, Beijing) | Chen, Kang Ping (Arizona State University)
Unconventional reservoirs after formation-stimulation treatments are always characterized by complex fracture networks with a wide range of length scales and topologies. Accurate simulation on multiscale discrete-fracture/matrix interaction during transient productive flows for such reservoirs is challenging but important for reservoir evaluation, optimization, and management.
In this paper, we present a new enriched and explicit method for simulation on multiscale discrete-fracture/matrix modeling (EE-DFM) on structured grids to decouple the mesh conformity between the porous media and the fractures. A hybrid structured EE-DFM is first introduced, and enrichments for different scales of fracture segments are proposed to locally enrich the conventional approximation space for representing the pressure solution surrounding multiscale fracture networks. By appropriately selecting an asymptotic function to locally enrich the conventional approximation space, typical behavior of fluid flux around features in fractured media, such as discontinuities and singularities, can be directly captured. Simulation on complex multiscale fracture networks is achieved by using the superposition principle of the enrichments without introducing additional degrees of freedom and while maintaining computational efficiency. We demonstrate the accuracy and flexibility of the method by performing a series of case studies and comparing the results with simple analytical solutions as well as with conventional numerical solutions. The results of long-term well-performance case studies are used to show the good computational efficiency of the proposed method when the complexity of fracture networks is increased. The potential of the proposed method to be incorporated into the multicontinuum concept for solving nonlinear gas transport in a shale reservoir is presented. The present study provides a promising framework for real-field multiscale discrete-fracture models for unconventional-reservoir simulations.
Ongoing growth in the volume of raw data generated by digitized oil and gas operations has been widely documented (Spath, 2014). What may be less apparent is that the industry is also authoring dramatically more unstructured content--interpretations, learnings, case studies, etc.--on an annual basis. This is not surprising, as anecdotal evidence suggests that most decisions are taken on the basis of unstructured data (Quaadgras & Beath, 2011) (Garland, 2017) (Palkowsky, 2005) (Haines, Shaughnessy, & Briggs, 2006) (Hollingsworth & Schey, 2017). At the Society of Petroleum Engineers, the number of new papers published annually has followed an exponential growth curve that doubles approximately every 10-11 years, beginning as far back as the early 1950's. Beyond books, journals, and conference papers available through the OnePetro digital library, SPE content comprises articles from print (the Journal of Petroleum Technology), digital-only publications (Oil and Gas Facilities, The Way Ahead and HSE Now), a variety of general-interest web pages, and technical resources (PetroWiki and SPE Connect). Well over 200,000 distinct items--papers or web pages--are available through the SPE's web sites as of May 2018.
Eibergen, Nora (The Dow Chemical Company) | Maun, Philip (The Dow Chemical Company) | Caldwell, Brittany (The Dow Chemical Company) | Widera, Imke (The Dow Chemical Company) | Morris, Brandon E. L. (The Dow Chemical Company) | Wunch, Kenneth (The Dow Chemical Company) | van der Kraan, Geert M. (The Dow Chemical Company)
The pipelines and vast infrastructure required for the production and transport of oil and gas are largely constructed of carbon steel. This material is highly susceptible to damage and failure as a result of direct or indirect Microbially Influenced Corrosion (MIC). One approach to reduce and/or remediate MIC is the application of microbicides to affected assets such as storage tanks, pipelines, heat exchangers and pumps. The objective of this paper is to generate efficacy data for biocidal formulations against corrosion-associated biofilms grown under anoxic and flowing conditions, which is difficult to obtain due to the distinct nature of biofilms and growth conditions. This data can be more representative when mimicking petroleum and water transporting pipelines. Thus, to facilitate the testing and comparison of products that successfully attenuate MIC under field-relevant conditions, a method that allows consistent corrosion measurements to be made, for corroding biofilms grown on steel surfaces under flowing and anoxic conditions, has been developed. This method utilizes microorganisms that were enriched on carbon steel from a North Sea sediment sample that, when grown in recirculating flow circuits, can generate corrosion rates of up to 65 mpy after four weeks of growth. The samples taken for the enrichment of corroding cultures came from a low tide anoxic sediment sample (black sand). In this presentation and paper, this method and its application to the benchmarking of field-relevant biocidal chemistries in MIC control experiments are described. Attention will be given to the reproducibility of the method as well. Distinct differences can be observed in biocidal performance against biofilms developed on metal surfaces.
A single well biopolymer injection test has been performed to investigate the stability of the biopolymer Schizophyllan under reservoir conditions. Laboratory tests of the Schizophyllan biopolymer prior to field test did show microbial degradation, and an environmentally qualified biocide was selected to be injected together with the biopolymer. The objective of this paper is to focus on the microbial aspects of using biopolymers for EOR (Enhanced Oil Recovery) by performing an extensive microbial analysis program of injected and produced water samples both prior to and after injection of the biopolymer into the reservoir. Multiple samples at different stages during the field test were collected using sterile and anaerobic methods to investigate any change in microbial community and evaluate any microbial degradation of the biopolymer. Analyses show that the biopolymer was not biodegraded during the shut-in period due to presence of biocide. However, microbes able to degrade the biopolymer Schizophyllan were present and could have biodegraded the biopolymer in the absence of active biocide. The microbial community changed in the area affected by biopolymer injection during the field test.
The current oil price scenario is strengthening the industry’s attention towards a more efficient energy usage. This paper shows the energy saving results obtained from field application of an innovative tool for the integrated production optimization of surface facilities based on a genetic algorithm. The objective function of the tool is tailored for each of the described case studies in order to increase field production and reduce energy consumption. The presented tool integrates well performances, gathering system calculation, and process plant simulation in order to optimize the field configuration with a global perspective. Conflicts and interactions between variables, constraints, and operational limitations are balanced and solved holistically by the optimization tool. For each of the field application case studies presented a tailored energy efficiency objective function is defined to optimize production and energy consumption. A powerful evolutionary algorithm searches for the optimum field configuration that represents the best trade-off between efficient usage of energy resources and production maximization. The integrated production optimization tool has been applied on different fields with the aim of simultaneously increasing the energy efficiency of the assets and optimizing production. The benefits of the integrated optimization tool to boost energy efficiency have been proved on an offshore field application. The action suggested from the optimization tool permitted production increase, reducing the global energy losses of the system. A second application is presented, where a significant energy saving has been achieved by the optimized configuration suggested from the tool to recover production after a process upset. All the described applications show a relevant energy saving in terms of primary energy consumption, associated with the increase of field production. This paper describes an innovative approach to increased energy efficiency in oil and gas industry operations. The application of the integrated production optimization tool showed its benefits by improving process and equipment operations and reducing associated operating costs without capital expenditures on energy efficiency.
A Parallel Enriched Algebraic Multiscale Solver (PEAMS) for simulation of flow in heterogeneous formations with high contrasts is introduced. Built on the recently developed enrichment strategy for single processing algorithms, i.e., EAMS of Manea et al. (2016), the PEAMS describes an efficient parallel implementation procedure as to how to enrich a given multiscale formulation with additional local basis functions. These additional basis functions, constructed in parallel computational platform, aim to resolve large error components for a generic fine-scale system with no right-hand-side term. The design and computational overhead of the enrichment kernels in shared-memory parallel environments are discussed in detail. The robustness and scalability of PEAMS are then illustrated for highly heterogeneous and anisotropic 3D multi-milion-cell reservoir models. The presented results show that, by adding only a few locally-supported complementary basis functions, the convergence of the original multiscale method is significantly enhanced. This is achieved with incurring a marginal overhead in the complexity to the coarse-scale operator. Moreover, in shared-memory parallel environments, it is shown that both of the enrichment procedure and the resulting enriched solver are scalable. Therefore, PEAMS casts a promising framework for robust iterative multiscale formulations for real-field applications, where parallel processing architectures are essential.
Yang, Zhao (PetroChina) | Fenjin, Sun (PetroChina) | Bo, Wang (PetroChina) | Xianyue, Xiong (PetroChina) | Wuzhong, Li (PetroChina) | Lianzhu, Cong (PetroChina) | Jiaosheng, Yang (PetroChina) | Meizhu, Wang (PetroChina)
Compared with the conventional oil and gas reservoirs, hydrogeological gas controlling process linking CBM accumulation, enrichment and high yield is one of the important scientific problems for the development of a CBM field. Previous research results are mainly focused on the impact of hydrodynamics on CBM dissipation, preservation and enrichment, whereas relatively less work has been done on the quantitative evaluation of the hydrochemical field of CBM and establishing evaluation indicators of CBM enrichment. Therefore, taking BQ Well area of Hancheng block in east Ordos Basin as an example, this paper tried to initiate a systematic analysis of the controlling function of hydrogeological conditions on the enrichment and high yield of CBM in the study area. Hydrological evaluation indicators for hydrocarbon enrichment zones are established and two favorable hydrocarbon enrichment zones are optimized. It is of great significance for the established analytical method of hydrogeological rule on the studies of CBM enrichment characteristics and development in Hancheng CBM block, and subsequent exploration & development in the neighboring blocks.
Firstly, the relevant principle of hydrodynamics is applied to identify substantive parameters, such as measured in-situ reservoir pressure and CBM reservoir water level in the production wells to calculate the reduced water level and analyze groundwater level distribution characteristics; secondly, combined with the analysis of groundwater water types, the sources of the produced water from coal beds are identified, and the sealing property of the reservoir is demonstrated; on this basis, the study area is divided into the weak runoff zone and the stagnation zone. It is considered that the runoff intensity is relatively weak and the sealing capability is good in the study area, with no external water intrusion; finally, it is considered that, through integrated studies on the hydrochemical field, the desulfuration coefficient and sodium chloride coefficient can reflect the diversity of CBM reservoir conditions in a more elaborated way. Hydrological indicators based on hydrochemical characteristics are established, and two favorable enrichment zones are predicted.
This work proved that hydrogeological features of CBM reservoirs are able to characterize their accumulation conditions elaborately. In particular, the establishment of hydrological indicators can classify favorable enrichment zones and hereafter guide following CBM exploration & development. This methodology has been satisfactorily applied in BQ well area of Hancheng block where the data of gas bearing capacity is limited. High single well production rates have been obtained in the two predicted favorable enrichment zones. The hydrological indicators established in this paper are expected to be popularized and applied in other well areas of Hancheng block, which may accelerate the overall exploration & development progress in this block.
Determining the redox conditions of pore fluids during the deposition of organic-rich sediments is an integral part of reconstructing the depositional environment of source rocks. Multiple geochemical tools including degree of pyritization and trace metal enrichment are utilized to evaluate the presence of oxygen and sulfide during deposition. In this publication the measurement of dolomite Fe-content was investigated as a potential tool for depositional environment reconstruction. In anoxic sediments, sulfate reducing bacteria (SRB) metabolize organic matter by reducing sea-water sulfate then release bicarbonate and H2S into pore fluids as byproducts. Pyrite and carbonate minerals, especially dolomite, will precipitate from the interaction of SRB byproducts with ions readily available in the pore system (Ca, Mg, Mn, and Fe). Consequently, the composition of organogenic dolomite will reflect the relative availability of these ions in sediments. Dolomite precipitated in Fe-limited systems (high degrees of pyritization or low detrital input) will be Mg-rich. Conversely, dolomite precipitated in sulfide-limited systems (moderate to low degrees of pyritization or high detrital input) will be Fe-rich.
The viability of Fe substitution in dolomite as a measure of depositional iron availability was tested in the Marcellus Formation. A core from northern Pennsylvania was analyzed using powder X-ray diffraction, X-ray fluorescence, and SEM imaging. The amount of Fe substitution in dolomite was quantified from the unit cell dimensions using X-ray diffraction. Samples with the lowest Fe content in dolomite contained the most total organic carbon (TOC), biogenic silica in thin section, and the highest enrichments of Mo. Samples containing Fe-rich dolomite correlated with moderate TOC, lacked biogenic silica cement, and were moderately enriched in Mo. Preliminary results indicate Fe content in organogenic dolomite does reflect Fe availability during precipitation, however, the absolute amount of Fe substitution is as of yet uncalibrated with degree of pyritization measurements.
The preservation of organic matter in black shale deposits is a result of the combination of multiple depositional mechanisms including rate of primary productivity, flux of detrital material, and redox conditions in sediment pore fluids (Aurthur and Sageman, 1994; Werne et al., 2002; Sageman et al., 2003; Bohacs et al., 2005). The relative importance of each of these mechanisms towards the ultimate preservation of organic matter has been studied using geochemical tools including degree of pyritization, morphology and size-distribution of pyrite, trace metal enrichment, and studies of the stable isotopes of both light and heavy elements (Raiswell et al., 1987; Wilkin et al., 1996; Murphy et al., 2000; Tribovillard et al., 2006; Duan et al., 2010). Detailed analyses of mineralogy are often excluded from geochemical studies despite the presence or absence of certain minerals is the result of chemical reactions occurring during deposition and early diagenesis.
Das, K. C. (IBM Research) | Sandha, S. S. (IBM Research) | Carol, I. (ETSECCPB, UPC) | Vargas, P. E. (REPSOL CTR) | González, N. A. (REPSOL CTR) | Rodrigues, E. (IBM Research) | Segura, J. M. (REPSOL CTR) | Lakshmikantha, M. R. (REPSOL CTR) | Mello, U. (IBM Research)
Reservoir Geomechanics is playing an increasingly important role in developing and producing hydrocarbon reserves. One of the main challenges in reservoir modeling is accurate and efficient simulation of arbitrary intersecting faults. In this paper, we propose a new formulation to model multiple intersecting cohesive discontinuities (faults) in reservoirs using the XFEM framework.This formulation involves construction of enrichment functions and computation of stiffness sub-matrices for bulk (rock mass), faults and their interaction DOFs. A sub-divisional scheme has been developed, to perform volume and surface integrations. The sub-divisional scheme can efficiently handle most possible configurations of multiple intersecting/nonintersecting faults in 3D finite elements. In order to be able to model cohesive behaviour of intersecting faults, we have performed additional surface integrations which, to the knowedge of the authors, are not reported in the literature. For example, if an element is intersected by two cohesive faults, we compute 16 volumes an d 8 surface in tegrations for stiffness matrices and 4 surface integrations for force vectors, to form elemental equations. The current distributed implementation using C++/MPI can simulate very large meshes. Three-dimensional benchmark cases are presented to validate the accuracy of the approach, and the potential benefits in applications. The present study shows that interaction DOFs and their associated surface stiffness matrices play a significant role in accurate modeling of cohesive faults via XFEM.
Faults are geological entities with thickness several orders of magnitude smaller than the grid blocks typically used to discretize the domain. Due to frictional forces between the surfaces, the natural occurring faults in rock masses are cohesive. Cohesive faults may result in relative displacements in the plane of the fracture. Due to arbitrary and multiple occurrence of faults, many of them may intersect and result in complex 3D geometries. Intersecting faults affect the strength and deformability of rock mass and thus their accurate modelling is required to understand the geomechanical behaviour of reservoirs. Numerical modelling techniques can be classified on the basis of the procedure used to represent faults. Faults can be represented implicitly by using constitutive equation for the continuum and additional deformations due to opening/slip. The explicitly representation of faults may be done in various ways, the more classical one is via zero-thickness (or sometimes thin layer) elements inserted in-between element faces/edges while all nodal variables maintain the traditional meaning as regula displacements (Goodman et al., 1968; Gens et al., 1988). We do implicit representation of the faults using level set functions (Das et al., 2015). The discontinuity can cut the elements in arbitrary ways, which is captured using zero values of level set function. This approach can define the discontinuities with complex geometries. The jump in the displacement field near the fault plane is captured using appropriate enrichment function. For example, for rock faults modeling, ‘Heaviside function’ is used to enrich nodes (Wells and Sluys, 2001).