SUMMARY1. The temperature dependence of presynaptic processes involved in neuromuscular transmission was studied by rapidly increasing the temperature of cooled frog neuromuscular junctions by 4-10 0C using pulses from a neodymium laser. The temperature elevation was complete within 0 5 msec, and decayed back to control levels with a time constant of about 7-8 sec.2. Temperature jumps completed before nerve stimulation increased the quantal content and decreased the latency of the end-plate potential (e.p.p.). The Q10 for

Image-based Stokes flow modeling in bulk proppant packs and propped fractures under 1 highloading stresses.

Field tests of a real-time Drilling Advisory System (DAS) have demonstrated value in several drill well surveillance applications. This system receives drilling data and transmits recommended operating parameters to the driller using existing rig systems and Wellsite Information Transfer Specification (WITS) data records. Using this industry standard, DAS can be deployed to any suitable data acquisition system on the diverse rig equipment available in the industry. The DAS computer may also be connected to a company network to enable desktop viewing of the drilling recommendations in the office. The method embodied in the software comprises both a learning mode and an application mode. In learning mode, systematic changes in parameters are recommended to explore the operating space, and calculation of an objective function determines results. Complex decisions to change operating parameters such as weight on bit, rotary speed, and flow rate can also be made with the assistance of DAS via early detection of drilling dysfunctions which change with depth and formation. The operator's ROP (Rate of Penetration) management process is focused on MSE (Mechanical Specific Energy) surveillance, and the DAS process extends this methodology to a real-time operating system. DAS is designed to assist the driller by capturing and organizing real-time data without imposing on their judgment and control. It is intended to be a digital helper that enhances the driller's ability to interpret current drilling conditions and make effective decisions. Remote access capabilities and customized output to the driller's display were demonstrated in field trials, and key lessons from field trials have been implemented. The field trials included multiple hole sections in onshore and offshore wells across a wide variety of drilling conditions. In one example provided in this paper, the use of DAS provided 35% higher ROP when DAS was used to avoid drilling dysfunctions. Introduction In a recent paper by Dupriest and Koederitz from the 2005 SPE/IADC Drilling Conference ("Maximizing Drill Rates with Real-Time Surveillance of Mechanical Specific Energy": SPE 92194), Figure 1 was presented to illustrate the three basic regions on a drilling response curve. The chart shows that although operating above the founder point may provide slight increase in ROP, the system is operating in dysfunction and the WOB should be reduced to eliminate the dysfunction.

The ability to understand and optimize the exact circumstances by which fluids enter the wellbore is increasingly crucial to achieving effective and economic production. The well completion, the connection to the reservoir, must be designed and operated in accordance with the true physics of the near well flow environment. The ability to visualize such flows, then parameterize and extrapolate the results with realistic simulation models, affords a powerful advantage in creating well completions that are simple to install, reliable to operate, and, of course, deliver all the flow the reservoir is capable of yielding. This paper illustrates the use of advanced visualization in this process. Two examples are presented, featuring detailed images of flow through complex sand control completions hardware (gravel pack) and of flow through wormholes in acid-stimulated carbonate rock.

Pressure transient tests of wells completed in multi-layer reservoirs have always been and continue to be a challenge for interpretation. Hence, characterizing layer properties from well tests, and determining and monitoring individual layer performance in commingled completions are complex and intensive tasks which could have significant impacts on well and reservoir management. Without accurate assessment of stimulation effectiveness and dynamic skin mechanisms, potential gains in long-term production may never be realized through appropriate action. This paper discusses a hybrid approach for synergizing multi-layer pressure transient analysis with production logging analysis of flow and pressure profiles while accounting for carbonate matrix acidization physics. This approach uses two completely different but complementary tools, which are the existing multi-layer pressure transient analysis option in a pressure transient analysis package and a post-completion inflow performance analysis suite developed by the ExxonMobil Upstream Research Company to analyze carbonate acid stimulation effectiveness for RasGas wells. Based on field experience and acidized wormhole growth physics, RasGas and ExxonMobil jointly developed a new approach to multi-layer characterization using a workflow synergizing pressure transient analysis and inflow performance analysis to analyze post-completion well tests. A field example is described to illustrate the advantages and added value of enhanced understanding of strongly multi-layer producing reservoirs. Background RasGas is one of the major operators of the North Field, offshore Qatar. The North Field is the largest non-associated gas reservoir in the world. The subsurface formation of the North Field, Khuff, is a multi-layered carbonate formation. The Khuff reservoir is formed of four different and non-communicating reservoirs: K1, K2, K3 and K4. As in most carbonate reservoirs, the Khuff lithology is a complex stratification of limestone (much of which is moldic) and dolostone in which the permeability varies by several orders of magnitude. The huge variability of the Khuff reservoir lithology, sometimes even within the same flow unit, is demonstrated by the distinctly variable MDT pressure profiles in a producing (dynamic) reservoir. Defining flow units is often a challenge for geologists and petrophysicists. The work presented in this paper presents a practical approach to quantifying reservoir flow behavior by generalized flow units. Most RasGas wells are commingled producers across all four Khuff reservoirs. These wells are acid stimulated in multiple stages. Stimulations are designed so that some intervals (sub-layers) are treated more than others. This optimized stimulation design is driven by complex reservoir lithology, the large net pay of the reservoir to be treated, and operational requirements for safety and cost effectiveness. The integrated pressure transient/post-completion analysis technique described in this paper was developed based on the company's long experience in dealing with the challenges of monitoring and understanding the well and reservoir performance of commingled producers. Integrated pressure transient/post-completion analysis establishes the baseline performance of a well for proactive assessment of the underlying causes of changes in well performance over the course of production.