Controlled resonant interactions between two spinning waves in a turbulent, axisymmetric air jet are documented. Interactions betwen two helical waves with spinning mode numbers of +m and −m induced a cos(2mϕ) distortion of the mean cross-section. The shape and orientation of the distortion were predictable based on the standing wave pattern. Square and elliptical jets were produced in this way and the spatial distribution of the coherent large-scale motion is documented. The elliptical distortion was comparable in magnitude to a jet issuing from a 2:1 elliptical nozzle. A near-resonance case produced from spinning mode numbers of m = 0 and + 2 was also examined.

Interactions between large coherent structures are visualized with both schlieren photography in two air jets and dye photography in a water jet. The density difference needed for the schlieren technique is provided by an electrically heated wire ring surrounding the jet. External forcing with either single axisymmetric, single non-symmetric, combined axisymmetric or combined non-symmetric modes was applied. It was found that forcing the jet with a pair of different spinning modes leads to azimuthal distortions of the mean flow. This observation confirms and explains existing hotwire data. Simultaneous excitation with two axisymmetric modes may produce structures of higher modes or even cause structurally undistinguishable development. Streamwise structures are observed both in the unforced jet and in the axisymmetrically forced jet. They do not seem to be caused by a G6rtler instability from the concave curvature of the conventional nozzle, since they were also found in a jet flow from a specially designed nozzle with only convex contraction surface.

In this paper, a new enrichment scheme is proposed to model fractures and other conduits in porous media flow problems. Inserting this scheme into a partition of unity based method results in a new numerical method that does not require the mesh to honor the specific geometry of these subsurface features. The new scheme involves a specially designed integration procedure and enrichment functions, which can capture effects of local heterogeneity introduced by subsurface features on the pressure solution. The new method is also capable of modeling fractures with low as well as high conductivity. Another feature of the proposed scheme is that, even though two enrichment functions are used to model the permeability change at the two rock/fracture interfaces of a fracture, only one element partition is made for numerical integration. To demonstrate the accuracy and effectiveness of the proposed approach, production problems for wells that were stimulated or completed by longitudinal fracture, transverse fractures, and perforations are studied.

SUMMARY In this paper, the geomechanical factors that may affect injection processes in heavy oil recovery are investigated. To accurately capture the geomechanical effects, we employed a numerical formulation that allows fully coupling of nonlinear geomechanical deformation and multicomponent porous media flows. Two salient features of this new coupling formulation are the following: (1) all flow and geomechanical equations are solved implicitly in one single matrix equation, and (2) it allows reuse of matrices from both a traditional fully implicit multicomponent reservoir simulator and a nonlinear geomechanics simulator. The former feature ensures stable coupling between the reservoir flow and geomechanics, and the latter significantly reduces the programming work. Numerical examples are given to demonstrate the accuracy and convergence performance of the new formulation. The proposed formulation is then applied to model injection into heavy oil reservoirs. The numerical investigation revealed that geomechanical factors, such as in situ stress anisotropy and the uneven deformation of reservoir rock and attached impermeable rock, can result in skewed or nonuniform plastic strain and, hence, alter the sweep of the injected fluid. Coupled geomechanics simulation also gives rather different transient pressure response from that of uncoupled simulation. Copyright © 2012 John Wiley & Sons, Ltd.

Summary This paper presents a comprehensive and integrated workflow to design completions for a heavy-oil recovery process that involves injection and production through the same well. Unlike in traditional completion design, the transient effects are particularly important to consider while analyzing the long-term performance for these types of completions to capture the effect of variations or uncertainties in reservoir and fluid-flow characteristics over time. The proposed integrated workflow involves initial screening and selection of flow-restricting completions that can meet the desired injection and production performance based on a detailed wellbore hydraulics modeling tool. A select few completions are then analyzed for longer-term performance using a reservoir simulator that couples the flow-restricting nature of completions with flow in the reservoir. The use of best-in-art wellbore hydraulics model and reservoir simulator in a staged process yields an effective way to assess and optimize the completion design for these wells in a reduced time span. The workflow disclosed here can be used to design effective completions for a broad class of cyclic liquid-injection methods for heavy-oil resources.