Cumulative studies of enteral immune-modulating nutritional formulations report benefits in surgical critically ill patients such as burn, trauma, or gastrointestinal surgery populations. Conflicting data in patients with sepsis warrant concern and further evaluation; in particular, controversy seems to stem around the use of arginine. Glutamine is beneficial when given in high doses or via the parenteral route (>0.20-0.30 g/kg per day or >or=30 g/day). Providing both omega-3 and omega-6 polyunsaturated fatty acids is important in immune modulation. The best doses and combinations of immune-modulating components remain unclear.
Targeting more complex and challenging reservoirs in terms of stratigraphy and structure, makes improved geosteering precision a necessity. This is particularly true when targeting thin permeability streaks or avoiding thin dense layers in highly heterogeneous reservoirs. The challenges are even greater when these thin reservoirs are highly faulted and the risk of missing the target is higher. Applying a proactive approach for well trajectory optimization while drilling and using the most recent logging while drilling (LWD) technology such as distance to boundary measurements, real-time image logs integrated with other LWD logs and 3D structural/properties models, it is possible to maximize the wells value. Deployment of these new technologies allows tracking the "sweet spots" of the reservoir more efficiently as uncertainties related to the dip, thickness of the reservoir and fault/fracture occurrence are better managed. This approach saves time and money by reducing the chances of missing reservoir targets and therefore the need to sidetrack or drill a complete new well. Another benefit from these procedures is the well accessibility which is highly improved due to an increased in the borehole smoothness, which is achieved through better control of the well trajectory. In this paper, several examples will be shown for different scenarios in different oil fields/reservoirs in Abu Dhabi, U.A.E. Introduction Placing wells within thin targets needs an accurate way to estimate the position of the well trajectory with respect to specific reservoir features. Today, the means to determine the well position in space is further refined as a result of significant improvements in logging while drilling (LWD) measurements and interpretation workflow. With the raising number of high angle and horizontal trajectories drilled, an increasing number of wells are drilled based on the petrophysical and geological LWD information, such as distance to boundary, real-time image logs integrated with conventional logs and 3D structural/properties models. Optimizing the well path to insure maximum contact within the target also requires improved drilling technology and methodologies. Horizontal wells usually follow smoothly curving trajectories, gradually building up or dropping deviation angle as they are carefully planned to ensure that they penetrate the targets accurately. The introduction of rotary steerable drilling assemblies has enabled the drilling of those complex and accurate trajectories. Rotary steerable systems (RSS), with its inclination and deviation (D&I) measurements near the bit has made it possible to closely control the well trajectory while providing a significant improvement in data coverage, used for formation evaluation [1]. The latter is the result of the continuous rotation of the bottomhole assembly (BHA), which allows the collection of azimuthal data, as opposed to sliding intervals using motors. Several considerations must be taken into account when deciding to utilize the appropriate well placement technology. Among these, the cost of drilling the well, the possibility to side-track, the risk and associated cost of entering in a water zone, the uncertainties of the target reservoir. One should also consider uncertainties in true vertical depth (TVD), well trajectory, reservoir boundaries and fluid contacts, the possibility of faults and the overall capability to predict what is ahead of the bit. There is no single best fit for determining which well placement method to use, as different methods are used today depending on the geological setup and the complexity of the targets. This paper attempts to highlight some of the significant geological and petrophysical issues in planning and executing horizontal wells using several case studies from Abu Dhabi oilfields. These examples highlights real time decisions that were taken while the wells were being drilled as a result of geologic challenges encountered.
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