Analysis and Flow Modeling of Single Well MicroPilot* to Evaluate the Performance of Chemical EOR Agents

Cherukupalli, Pradeep Kumar; Horstmann, Dirk; Arora, Shyam; Ayán, Carlos; Cig, Koksal; Ramamoorthy, Raghu; Kristensen, Martin; Zaggas, John; Edwards, John E.

doi:10.2118/136767-ms

Cited by 6 publications

(5 citation statements)

References 11 publications

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“…[3]) were constructed to investigate the feasibility for effective pressure measurement in tight (<1.0 md) to ultralow (<0.1 md) formations where such sand formations generally have poor even little mud cake formed to significantly reduce continuous invasion consequently supercharging. Two mechanisms, continuous invasion with varying invasion rates by time and time-lapse effects which depend on when formation testing was conducted after the borehole was drilled and opened to wellbore muds, were cooperated into the simulation while pretesting.…”

Section: Preliminary Simulation Results Of the 3d Radial Probe For Prmentioning

confidence: 99%

Unlock Tight Gas Reserves in South China Sea by a Revolutionary Formation Tester

Yang¹,

Guo²,

Cai³

et al. 2014

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As interest grows in formations with permeability ranging from tight (<1.0 md) to ultralow (<0.1 md), formation testing and conducting drill stem tests (DSTs) become increasingly challenging and more costly. Formation testing using conventional probes has low success rates for pressure surveys and sample collection, long pumping times, and poor data quality that cause difficulty in fluid identification because of incomplete cleanup of filtrate. DSTs are often unsuccessful without sufficient inputs of permeability and fluid properties for optimization of testing plan. This paper presents case studies of a revolutionary new 3D radial probe that makes effective evaluation possible for unlocking tight gas reservoirs in the South China Sea.The tight gas formations have poor borehole condition for conventional probe sealing and testing. In the two case studies of this paper, a total of 25 attempts by two different conventional probes fail to seal. However, four stations of the 3D radial probe took less than 4 hours per station to successfully collect PVT-quality samples. Fast cleanup to flow pure formation fluids enabled better accuracy in real-time fluid identification, sampling assurance, and compositional analysis including CO2. Transient analysis indicated that all stations have <0.1-md/cp effective mobilities, with the lowest at 0.03 md/cp. Production prediction were conducted to assess the natural productivity. Comparison with DST results from neighboring wells show that this prediction has acceptable accuracy and is sufficient for crucial decision making. This enables the operator to avoid unnecessary DST stations and ensure optimal completion and well testing designs.Performance was compared against conventional modules. The advantages of the 3D radial probe over elliptical probes and dual-packer module in this kind of tight gas reservoirs are obvious and significant, with better efficiency, quality and operability such as applicable differential pressure, sealing capability, minimum storage, no exposure to borehole mud, and less sticking and plugging probabilities. Numerical modeling of an immiscible water-gas system with representative borehole conditions and reservoir properties of tight gas formations was conducted to investigate flow and pressure transient behaviors for operation optimization. Initial results of the simulations will be briefly discussed in this paper.

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Section: Preliminary Simulation Results Of the 3d Radial Probe For Prmentioning

confidence: 99%

Unlock Tight Gas Reserves in South China Sea by a Revolutionary Formation Tester

Yang¹,

Guo²,

Cai³

et al. 2014

All Days

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“…The workflow for modeling EOR MicroPilots was presented by Cherukupalli et al (2010). In brief, it consists of four steps, as illustrated in Figure 2.…”

Section: Modeling a Low-salinity Micropilotmentioning

confidence: 99%

“…The formation salinity is 4,800 ppm and we assume a mudfiltrate salinity of 15,000 ppm. Relative permeability data were estimated from radial conductivity measurements captured on an array resistivity log (for more details see Cherukupalli et al 2010;Ramakrishnan and Wilkinson 1999). We use these data as the base high-salinity curves and again construct the low-salinity curves from the parameter ranges in Table 1.…”

Section: Range Of Values Sourcementioning

confidence: 99%

“…For a vertical well with laterally homogeneous porosity and permeability the problem domain becomes symmetric, which is exploited in the simulations by considering only a half-circle grid. In constructing the MicroPilot grid we follow the approach outlined by Cherukupalli et al (2010) in which the grid density and the distance to the outer boundary are calibrated by comparison of single-phase solutions with analytical methods. Additionally, to further validate the grid, we perform a grid refinement study to assess the impact of numerical dispersion on the multiphase solutions.…”

Section: Range Of Values Sourcementioning

confidence: 99%

“…They covered aspects of the job design, execution, and log interpretation. Cherukupalli et al (2010) presented flow modeling of the first MicroPilot showing that the saturation changes measured by the logs could be successfully matched by a relatively simple model of the ASP process. Finally, Edwards et al (2011) recently reported on the second application of the technique, which was conducted in a light-oil carbonate reservoir using an alkaline-surfactant mixture as EOR fluid.…”

Section: Introductionmentioning

confidence: 99%

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Feasibility of an EOR MicroPilot for Low-Salinity Water Flooding

et al. 2011

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U.S.A., Over the past decade low-salinity water flooding has emerged as a viable enhanced oil recovery (EOR) method. Both laboratory tests and field trials have shown that injecting chemically modified water instead of seawater can lead to incremental oil recoveries. Although much research has been conducted, the governing physical and chemical mechanisms for this increase in recovery are not yet agreed upon, but are generally believed to involve some form of interaction between the rock, oil, and brine leading to changes in wettability, oil/water interfacial tension, or both.The relative uncertainty in the physics of the recovery process calls for a carefully staged screening and pilot program before committing to full-field implementation. The EOR MicroPilot* is a single-well piloting technique that enables rapid and inexpensive testing of EOR methods under in-situ downhole conditions. It is a log-inject-log technique conducted with a wireline formation tester (WFT). A small quantity of EOR fluid is injected and the resulting change in oil saturation is then determined based on a set of openhole logs, which are run both before and after the injection.In this paper we investigate the feasibility of a MicroPilot for low-salinity water flooding. Through simulation we show that the changes in oil saturation and salinity are measurable by the openhole logs. We further quantify the conditions under which a low-salinity MicroPilot is feasible in terms of the minimum measurable saturation changes and the contrast in salinity between the injected and resident brines. To assess the accuracy of the numerical solutions, we have conducted grid sensitivity studies as well as comparisons with analytical solutions to simplified 1D problems.The results of this paper are directly applicable to the planning of low-salinity waterflood pilots. The methodology proposed, based on the MicroPilot concept, can reduce piloting costs as well as reduce the time required between laboratory testing and field implementation. * Mark of Schlumberger

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Single-well In-situ Measure of Oil Saturation Remaining in Carbonate after an EOR Chemical Flood

Edwards

Ramamoorthy

Singh³

et al. 2011

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The MicroPilot* is a log-drill-inject-log sequence of operations designed to evaluate the improvement in oil recovery resulting from the addition of chemicals to the injected water. The fluid to be injected is transported downhole in a sample chamber and injected into the formation through a pencil sized drilled hole, with measurements of the resulting changes in saturation proximal to the well. This technique was first used during 2009 in Oman to perform an in-situ test of alkaline surfactant polymer in high porosity-permeability clean sandstone saturated in medium viscosity oil. This in-situ measurement is even more relevant for carbonates, as it eliminates the uncertainty associated with restoring mixed wettability in cores prior to laboratory enhanced oil recovery (EOR) floods. However executing a log-drill-inject-log sequence of operations in tight carbonates is more complex than clastics. The issues include small scale heterogeneity, presence of natural or induced micro-fractures, varying residual oil saturations, and the low permeability that requires injecting at pressures above the drilling fluid hydrostatic pressure. The operation and results of the first use of this EOR screening technology in carbonates is described in this paper in which an alkaline surfactant mixture (AS) was injected into a partially water swept 3mD permeability carbonate containing light oil. Aspects described include the mechanical process of drilling and injecting AS and the petrophysics of measuring changes of oil saturation at a small scale. The saturation changes are compared with other AS flood measurements in a neighboring well test using Single Well Chemical Tracer (SWCT) and cased hole logs. *Mark of Schlumberger

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Analysis and Flow Modeling of Single Well MicroPilot* to Evaluate the Performance of Chemical EOR Agents

Cited by 6 publications

References 11 publications

Unlock Tight Gas Reserves in South China Sea by a Revolutionary Formation Tester

Unlock Tight Gas Reserves in South China Sea by a Revolutionary Formation Tester

Feasibility of an EOR MicroPilot for Low-Salinity Water Flooding

Single-well In-situ Measure of Oil Saturation Remaining in Carbonate after an EOR Chemical Flood

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