When Should We Worry About Supercharging in Formation-Pressure-While-Drilling Measurements?

Chang, Yong Keun; Hammond, Paul S.; Pop, Julian

doi:10.2118/92380-pa

Cited by 21 publications

(9 citation statements)

References 8 publications

(19 reference statements)

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“…No large changes in contamination are therefore expected as a result of changing the circulation rate (Dewan and Chenevert 2001;Chang et al 2005), an expectation also supported by modeling. Fig.…”

Section: Fig 5-comparison Of the Gc-derived Composition Of The Live mentioning

confidence: 82%

“…Also shown in the upper plot of Fig. 6 are the assumed mud circulation rate (nominally 450 gal/min) and predictions for the supercharge pressure, the mudcake thickness, and the filtration rate using the models described in Chang et al (2005) and the mud properties listed in Table 3, which correspond approximately to the properties of the mud used in the field experiments described later. Using the predicted filtration rate and an extension of Hammond's contamination analysis (1991) originating with Sherwood and Stone (2001) to account for a leaky mudcake, 3 the level of contamination in the sampled stream may be predicted as shown in the lower plot of Fig.…”

Section: Effect Of Time After Drillingmentioning

confidence: 99%

“…The drilling profile, times at which the samples are acquired, supercharge pressure, mudcake thickness, and mud-filtration rate at the sampling depth are shown in the upper graph. The mud-filtration model employed is described inChang et al (2005). The simulation used the water-based mud and formation properties given in…”

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confidence: 99%

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Characterization of Sampling-While-Drilling Operations

Villreal

Pop

Bernard

et al. 2012

SPE Reservoir Evaluation &Amp; Engineering

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The while-drilling environment poses several potential challenges to acquiring representative formation-fluid samples; in particular, sampling times are expected to be restricted (perhaps severely) and dynamic filtration conditions are expected to predominate. With the aim of formulating effective strategies for sampling-while-drilling (SWD) operations, it is natural to seek answers to at least the following questions: When should samples be acquired-immediately after drilling the formation when invasion is shallowest, or after some time when the mudcake is more mature? What is the effect of circulation rate on sample quality? What levels of sample quality are achievable under while-drilling conditions?The first part of the paper describes the SWD tool used to investigate the questions posed. The tool is composed of the following components: a probe module; a pump-out module, which contains within it fluid-property sensors, including a resistivity cell and a 10-channel optical spectrometer; sample-capture modules; and a power-generation module consisting of a dedicated mud turbine and alternator that provide the required pumping power to the sampling tool.The second part of the paper is devoted to the description and analysis of a series of tests performed to characterize SWD operations. In particular, the following aspects were studied for their effect on sampling efficiency and sample contamination: time after drilling, mud-circulation rate, ceasing and resuming pumping operations as a means of mitigating sticking risk during protracted pumping operations, and the integrity of samples captured under drilling conditions. All tests were performed in water-bearing formations drilled with a water-based mud. A wireline sampling (WLS) tool was run after the while-drilling tests were completed in order to compare the performance of the two sampling tools.The principal conclusions derived from the tests conducted are that present-day sampling technology can be made to survive and operate effectively under drilling conditions, and that there appear to be substantial advantages to acquiring samples soon after drilling a formation. SWD-Tool DescriptionThe SWD tool as currently configured consists of the following modules: a probe module, a pump-out module, sample-capture modules, and a power-generation module (see Fig. 1). The probe module is a modified version of a formation-pressure-while-drilling tool . Modifications to the formation-pressure-while-drilling tool include a larger-diameter probe (0.82 in. in diameter compared with 0.56 in. for the pressure-while-drilling tool), a larger surface area of the sealing packer, a sampling flowline extending from the probe to the bottom of the tool, and a pair of valves whose purpose is to isolate the pressure-measurement section from the rest of the tool during sampling. In normal operation, the isolation valves are positioned to allow the probe to communicate with the pressure-measurement flowline. The pump-out module contains an electromechanical direct-drive pump, pressure ...

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Section: Fig 5-comparison Of the Gc-derived Composition Of The Live mentioning

confidence: 82%

Section: Effect Of Time After Drillingmentioning

confidence: 99%

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Characterization of Sampling-While-Drilling Operations

Villreal

Pop

Bernard

et al. 2012

SPE Reservoir Evaluation &Amp; Engineering

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“…The surface-determined and PVT-laboratory-determined values are consistent for all wells considered (Tables 2 and 3). The optical spectrometer currently used in the while-drilling tool belongs to the first generation of downhole spectrometers that attempted to address fluid typing in real time through the determination of GOR (Dong et al 2002). With this spectrometer, an estimate of the GOR is made by measuring the relative magnitudes of the methane and oil peaks located, respectively, at approximately 1670 nm and 1725 nm on the hydrocarbon spectrum (Dong et al 2002;Mullins 2008).…”

Section: Discussionmentioning

confidence: 99%

“…The pumpout module contains an electromechanical direct-drive positive-displacement pump, pressure gauges to measure the pressure at the probe during sampling and the pressure at the outlet of the pump, a resistivity cell capable of measuring the flowline-fluid resistivity and temperature, and a 10-channel optical spectrometer ruggedized for use during drilling operations. The type of optical spectrometer used is well known in WLS operations, where it is primarily used for the real-time determination of sample contamination and for estimating the in-situ gas/oil ratio (GOR) of the sampled fluid (Dong et al 2002). The electromechanical pump is composed of a reciprocating-piston displacement unit actuated by a ball screw coupled with an electric motor.…”

Section: Tool Descriptionmentioning

confidence: 99%

Sampling While Drilling: An Emerging Technology

Pop

Villareal

Bernard

et al. 2014

SPE Reservoir Evaluation &Amp; Engineering

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Even though it is the early days of the realization of samplingwhile-drilling (SWD) as a service, a picture of what might be achievable in practice is beginning to emerge. Previous SWD experience has demonstrated that the sampling process may be controlled sufficiently well that relatively clean samples may be acquired when sampling aquifers drilled with water-based muds (WBMs), and it has demonstrated that the SWD tool and sensors used are capable of operating effectively while withstanding the drilling process. On the basis of this experience, operational guidelines have been formulated, particularly regarding the most opportune time to sample during the drilling process.The first part of the paper describes SWD in a high-angle appraisal well drilled to assess the continuity and quality of several target sands and to establish the degree of continuity of these sands with the main field. The well was drilled by use of an oilbased mud (OBM). Samples would be acquired after the well had reached total depth so that the most appropriate sampling points could be identified by means of openhole logs. Multiple water-, oil-, and gas-bearing formations were identified. Sampling duties were split between the SWD tool and a drillpipe-conveyed wireline sampling (WLS) tool in an attempt to rationalize the sampling program of the well. To enable a comparison of the relative performance of the two tools, two oil-sampling stations were chosen where multiple samples would be acquired under similar operating conditions by both tools. In addition, water samples were collected at two stations by the SWD tool and scanning was performed at one (wet) gas station to confirm the formation-fluid type. Laboratory analysis of the oil samples at the common stations showed that the contaminations and fluid properties of the samples acquired by the two sampling tools were very similar.The second part of this paper describes results obtained in an appraisal well and sidetrack in a different field. Both pilot and sidetrack were high-angle wells drilled by use of OBMs. The purpose of these wells was to identify and evaluate the commercial potential of unproduced hydrocarbon-bearing zones. Both wells were drilled to total depth before conducting sampling operations, and no wireline operations were planned in either well. Five oil samples were acquired in the pilot well in two zones, and four oil samples and two water samples were recovered in the sidetrack.The results obtained during the SWD operations described suggest that it is possible to consistently acquire quality formationfluid samples during drilling operations, even under less-than-optimal sampling conditions and strict time-on-station constraints. The quality of the samples recovered is sufficient to perform reliable pressure/volume/temperature (PVT) analyses.

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Formation Testing

2018

Petroleum Engineering

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When Should We Worry About Supercharging in Formation-Pressure-While-Drilling Measurements?

Cited by 21 publications

References 8 publications

Characterization of Sampling-While-Drilling Operations

Characterization of Sampling-While-Drilling Operations

Sampling While Drilling: An Emerging Technology

Formation Testing

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