Advanced Materials Research Vols. 18-19

Abstract: Polyurethane samples were prepared from rubber seed oil monoglyceride (made by reacting rubber oil with glycerol) and diiosocyanates (hexanethylene and toluene diiosocyanates). Polyurethane composites were made by compression moulding using biofibres; sisal, jute and banana; in random and unidirectional orientations at different fibre lengths and loadings, as reinforcing elements. The composites were characterized in terms of tensile and flexural strengths and moduli, thermal stability and morphology of fractured surface. The values of the measured mechanical properties (tensile and flexural) of the composites were about 3-fold higher than the properties of the unreinforced polyurethane samples, suggesting good reinforcement by the biofibres. The absence of fibre-pull-out on the scanning electron micrographs of the fractured surface provides evidence in support of good adhesion between the biofibres and the polyurethane matrix. The thermal stability of the composites was lower than for the fibre but higher than for the unreinforced polyurethane.

Abstract: The physical properties of some Nigerian clays were studied in order to determine their suitability for a variety of industrial applications. From the analysis, the specific gravity of Ukpor and Ahoko clays were 1.89 and 2.26 respectively and the Plasticity Index 26.05% and 22.45%, drying shrinkage was 18.90% and 8.2% and particle size distribution showed that the samples are clays. The results show that the physical properties of the clays are within the specifications for kaolin clays and are suitable for industrial uses.

Abstract: Compression test specimens were produced from the composite material of fibre reinforced polymer (FRP). These specimens were tested on the compressive testing machine. The results obtained showed that 5% coconut fibre volume fraction with 95% volume fraction of polypropylene matrix gave compressive strength value of 39.3 Mpa. However, it was observed that when 15% volume fraction of CaCO3 and wood flour filler each were added, the compressive strength increased from 39.3 Mpa to 53.3 Mpa and 39.3Mpa to 43.7Mpa respectively. This observation was discussed in respect of the two fillers.

Abstract: In this paper, a finite elment-eigenvalue method is formulated to solve the finite element models of time dependent temperature field problems in non-homogeneous materials such as functionally graded materials (FGMs). The method formulates an eigenvalue problem from the original finite element model and proceeds to calculate the associated eigenvectors from which the solution can be obtained. The results obtained highly accurate and are exponential functions of time which when compared with the exact solution tended fast to the steady state solution.

Abstract: This paper compares the pressure drop profiles of both horizontal well producer and injector in a 5spot waterflood pattern. Dimensionless pressure distributions for each pattern were utilised. All computations were limited to conditions of unit mobility ratio; i.e., before water breakthrough condition. Results show that a normal 5-spot flood pattern, with a horizontal well producer, offers higher pressure drops, but early water breakthrough tendencies, than as an injector for the same reservoir and wellbore conditions. An inverted pattern, under the same conditions, produces clean oil for a longer time, before water breakthrough possibilities.

Abstract: The stability of gas injection in a layered reservoir drilled with lateral wells, is studied using a generalized pressure distribution-dependent mobility ratio expression. Stable injection guarantees clean oil production. The mobility ratio compared layers’ fluid velocities across a common permeable interface. Studies were based on injected gas compressibilities and viscosities only. Results show that injection stability is affected by (1) injected gas properties, and (2) injection layer; i.e., whether gas cycling (bottom layer injection) or gas injection (top layer injection). Gas cycling tends to exhibit more instability than gas injection operation.

Abstract: Well engineers face ever increasing technical challenge of drilling in complex environments and the use of Managed Pressure Drilling(MPD) techniques to control annular pressure for improved drilling performance in the oil industry has growing interest[1-4]. Understanding hole cleaning and controlling annular pressure in this complex environment is becoming increasingly important for a range of applications. The Virtual Well Engineer[VWE] has been identified as the engineering tool to address these issues in order to deliver a successful MPD operation. The VWE is the product name for a suite of well planning , monitoring and simulation packages with focus on Managed Pressure Drilling includng underbalanced drilling that allows the well engineering team to interact with virtual reality. Recent works initiated by the Well Engineering Group at The Robert Gordon University have extended the knowledge of multiphase flow in a drilling annulus through the tracking of the transient multiphase flow pattern prevailing and effects on hole cleaning , the pressure profiles and identification of hot spots in concentric and eccentric annular sections . The mechanistic models developed at RGU form the core algorithms for the VWE. This paper presents the architecture and functional capabilities of the VWE – HydraulicsDTS™ , which is used in simulating well operations.

Abstract: Formation impairment due to fines migration during drilling and production continues to cause injectivity or inflow reduction. In high permeability sandstone formations or sandpacks, fines migration pose major concerns in the oil industry as it leads to reduction in oil/gas production. The problem is further enhanced in mature reservoirs where increased water ingress and multiphase production aggravate the fines mobilisation and migration. Proper fines management can optimise productivity, safeguard facilities and reduce well maintenance cost. Today’s core flood tests as part of risk assessment limit tests to single phase or at best two-phase oil/water flow. This paper presents the unique technique adopted to analyse fines migration mechanisms in a true multiphase environment. The technique integrates CFD and 3-D reservoir simulation concepts to define and quantify the effects of different operating conditions on discretised reservoir blocks. From the results obtained detailed mapping of prevailing pore blocking mechanisms and corresponding impairment profiles are presented as functions of operating conditions and completion strategies. The paper introduces a parallel experimental programme being initiated at The Robert Gordon University(RGU) to validate the simulation predictions. The paper is concluded with suggestions (supported by flow efficiency case studies) on contemporary innovations in fines management ranging from a radical use of expandable screens (ESSTM) or expandable slotted liners (ESLTM) or the intelligent VSSTM Screen to specialist application of glass or ceramic beads for pore diameter control and near wellbore reinforcement to initiate secondary filtration