Hadi Belhaj

Numerical Investigation of the Prospects of High Energy Laser in Drilling Oil and Gas Wells

Abstract Lasers are expected to provide a less expensive alternative to conventional machining and have found wide spread use in many industries. However, the physical phenomena involved in many laser applications are not fully understood. A better and more quantitative understanding of the physical mechanisms governing these phenomena will diminish the need for extensive trial and error experiments. Most of the theoretical models available in the literature have dealt with quasi-steady material removal using a continuous wave laser. This article presents a numerical model to predict the transient thermal behavior process of rocks under the influence of a pulsed laser. A wide range of parameters were considered in this study, the laser powers were varied from 0.1 to 100 kW and the lasing time was varied between 1 and 100 s. One of the results presented in this article shows that limestones consume less energy per unit volume of material removed as compared to sandstones. A comparison between the findings of this numerical study and published experimental data is also presented and shows a qualitative agreement. Finally, it is shown that numerical modeling can be useful in scaling up laboratory results to field applications.

A New Two Phase Extension of Modified Brinkman Formulation for Fluid Flow through Porous Media

In porous media research, Modified Brinkman’s equation is a very recent development. It is important as it incorporates the concept of viscous effect to inertial effect in a fluid flow system when Darcy’s, Forchheimer’s and Brinkman’s terms are brought all together. So far, researchers have developed the modified equation in its two-dimensional forms; however, limited to only one phase. In reality, petroleum reservoirs experience the multiphase conditions. Therefore, the simulation of a multidimensional, multiphase scenario is mostly desired, the highlight of this paper. The paper presents the formulation of two-dimensional, transient pressure and saturation equations for oil and water phases, one equation for each phase. The difference between phases is noticeable explicitly in their respective saturation, permeability, viscosity and velocity terms. The equations are then solved numerically to generate relative permeability curves. The simultaneous solution of pressure and saturation terms in the governing equations required additional relationships: the phase saturation constraint and capillary pressure as function of saturation. Finally, the numerical results are compared and validated with the experimental results. The implication of this study is manifold. The formulated equations including the solution part for the multiphase conditions are new. The new comprehensive model will describe fluid flow in reservoirs prone to high velocity or fractures more accurately than ever described by Darcy’s or other aforementioned equations.Copyright

Modeling Horizontal Well Oil Production Using Modified Brinkman’s Model

Horizontal well oil production has been numerically studied by using the Modified Brinkman’s Model. This model has been used along with the Darcy-Weisbach pipe flow equation in modeling of coupled porous medium/pipe flow. The results include seepage flow rate along the horizontal well, velocity distribution, pressure drop, and production pressure drop between the two ends of the horizontal well. They have been compared with those from Darcy model. It is found that when the fluid’s viscosity is low, there is a big difference between the results from the two models. However, when the fluid’s viscosity is high, the difference tends to vanish. In addition, two striking findings have been observed: (a) the curves for the distribution of the seepage flow rate along the pipeline are more flat than that from Darcy model. However, a higher viscosity makes the curve more uneven. This reverses the trend from Darcy model. (b) The velocity in the pipe is more uniform by MBM than that by Darcy model. The curves of V ~x become more uniform in the pipe when the fluid has a lower viscosity. This again reveres the trend from the Darcy model.Copyright

Physical and Analytical Studies of Sand Production from a Supported Wellbore in Unconsolidated Sand Media With Single- and Two-Phase Flow

Use of expandable technology for sand control has rapidly grown in recent years. While several expandable systems have been developed, assessment of their long-term performance and effectiveness has hitherto not been objectively completed. To address some of the concerns and uncertainties on this front, this paper provides criteria for the assessment of sanding from well-bores completed by expandable completion techniques. It also provides an in-depth understanding of the mechanism under which expandable screens control mobilization of sand grains. A series of experiments were conducted using hollow cylinder unconsolidated sand samples. The primary objective was to assess the influence of the opening size relative to the grain size in dictating the operational limits. A stiffener, representative of a general expandable completion technique, supported the central hole. The stiffener contained a network of small perforations. Experiments were conducted on both single- and two-phase flow media. This was to explore the possible effect of a second phase in sand production in the presence of the stiffener. Experiments showed that the mobilized friction between the grains plays a major role in preventing sand production. The experiments also confirm that even with a large aperture size of an order of magnitude greater than the maximum grain size, sanding did not take place under routine operational conditions in a two-phase medium. On the contrary, instant sanding from the sand-pack in single-phase experiments took place, which emphasized the important role of capillarity.

Experimental Study of Sand Production from a Supported Wellbore in Weakly Consolidated Sandstone

Deployment of expandable technology for sand control is experiencing rapid growth. While several expandable systems have been developed, assessment of their long-term performance and effectiveness has not. To alleviate some concerns and uncertainties, criteria are provided in this paper for assessing the possibility of sanding in wellbores that employ reticulated expandable completions and to illustrate an in-depth understanding of the mechanism under which such screens may prevent sand grain mobilization. To investigate these issues, a series of experiments were conducted using hollow cylinder synthetic sandstone samples involving both fine- and coarse-grained sands. A stiffener of two different opening sizes supported the central hole to check if sanding takes place and if so, how great the influence of the opening size relative to the grain size is in dictating the operational limits. The experiments on weakly-consolidated sandstones showed that expandable completions were successful in preventing any shear failure around the wellbore. Under excessive drawdown/depletion, volumetric failure (pore collapse) proved to be a plausible failure mechanism in the material. Nevertheless, much less sanding occurred, and this improvement was attributed to grain-to-grain friction, enhancements of effective stresses at the wellface, and some degree of conservation of the original structure of the material, although at the state of pore collapse.