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Summary Development of simultaneous downhole flow-rate/pressure measurementequipment has permitted better determination of reservoir properties. Application of such equipment to layered reservoirs allows determination ofindividual layer properties. This paper reviews state-of-the-art pressure andflow-rate devices, discusses the advantages and limitations of specificequipment, and ad-dresses the need to evaluate current tools and areas forfuture research. Introduction Various dynamic downhole measurements (e.g., pressure, flow rate, temperature, and density) are routinely performed simultaneously bywell-testing and production logging devices. Production logging surveys understabilized flow (or shut-in) conditions are useful to diagnose and monitor wellperformance. Such surveys can be conducted by dynamic tool passes across theformation and/or by stationary measurements between producing zones. Stationaryreadings may also be used to measure the reservoir's transient response toflow-rate changes. Results are used to quantify well performance. Anotheruseful application of simultaneous performance. Another useful application ofsimultaneous flowrate/pressure measurements is the determination of the effectsof reperforating on reservoir performance. Simultaneous flow-rate and pressuremeasurement is a powerful technique for reservoir property determination inboth single- and multilayered reservoirs. Such measurements may be obtainedwith tool combinations ranging from "full-spectrum" production loggingstrings to much more abbreviated tool configurations. The purpose of this paperis to describe state-of-the-art equipment for the measurement of downhole flowrate and pressure. Advantages and limitations of current tools are discussed. This paper illustrates how some inherent measurement errors can affectcomputation of reservoir properties from pressure-transient test analysis. Future research areas are also addressed. Pressure/Flow-Rate Equipment Combinations Pressure/Flow-Rate Equipment Combinations Sensitive electronic pressure devices, such as the quartz crystalgauge, have revolutionized pressure-transient testing. 3.4 The ability tocombine downhole pressure-transient and flow-rate measurements simultaneouslyallows improved analysis of conventional pressure-transient tests and oflayered reservoirs. pressure-transient tests and of layered reservoirs. Theproper combination of downhole pressure gauge and flowmeter depends on downholeflow parameters and the type of information required. For example, pressure/flow-rate tools for a conventional buildup test will differ from thoseon a string used to run a full-spectrum production log before buildup testing. The choice of spinner-type flowmeter will frequently he dictated by suchdownhole conditions as rate, water cut, wellbore deviation, and casing size. Whether a basket-type flowmeter is required depends on the same flow conditionsand on the type of logging data desired. The choice of a sensitive quartzpressure gauge over another device is likewise dictated by test designconsiderations. A quartz pressure gauge is a popular choice for mostpressure-transient testing applications because of its high degree ofpressure-transient testing applications because of its high degree of accuracyand sensitivity. Such gauges also are commonly used for absolute pressuremeasurement during production logging operations. One major wireline contractoruses a strain-gauge sensor to make combined pressure and fluid-densitymeasurements during production logging. This device can he used alone or withthe more production logging. This device can he used alone or with the moresensitive quartz gauge when more accuracy for pressure transient analysis isrequired. Flowmeters are currently limited to several varieties of spinnertools. The conventional "continuous" spinner tool and a"turbine" spinner analog perform well during production loggingoperations in high-rate wells. Therefore, they frequently are used mpressure-transient testing applications. The "fullbore"pressure-transient testing applications. The "fullbore" flowmeter (Fig.1), a variation of the conventional continuous flowmeter, is designed toprovide a more representative fluid-velocity measurement in multiphase flow, especially in deviated wells. The fullbore flowmeter uses various bladediameters to accommodate the full range of casing sizes. Rate measurement inlow-rate wells, especially in deviated offshore wells, is enhanced by use ofone of a variety of basket-type flowmeter. Such devices are designed to measureall flow with petals that seal against the casing. A more recent variation ofthe petals that seal against the casing. A more recent variation of the basketflowmeter, the Inflatable Diverter Flowmeter (Fig. 2), is designed to provide amore linear tool response. Equipment Evaluation Flowmeters. Continuous Spinner Continuous spinners derive their name fromthe fact that multiple logging passes are usually made under stabilized flowconditions to produce a continuous log of spinner response vs. depth. Suchtools produce electrical pulses as the impeller is rotated; pulse rate isproportional to rotational speed, which in turn is related to fluid velocity. Spinner threshold velocity is the fluid velocity below which impellerrotational speed is zero. Positive threshold values result from the effects ofmechanical friction and fluid properties. Low threshold velocities are moreimportant in well-test analysis than in production logging applications becausetools are stationary during production logging applications because tools arestationary during pressure-transient testing and receive no benefit oftool-line speed, pressure-transient testing and receive no benefit of tool-linespeed, as occurs during dynamic passes. Retaining acceptable threshold valuesdepends heavily on proper tool maintenance. Fig. 3 illustrates turbine spinnerresponse from flow-loop measurements for monophasic oil in 6.5-in.-ID pipe. Wellbore deviation, even in single-phase flow, creates scatter in the data atrates below about 75 gal/min (2,550 B/D). A linear data regression for allrates and angles gives a threshold rate of about IS gal/min (510 Fig. 4 demonstrates the additive effect of biphasic flow and wellboredeviation on data scatter. Spinner response is angle-dependent at all ratesinvestigated. At rates below 90 gal/min (3,060 B/D), localized velocityreversals create reversals in spinner rotation, even though the tool is wellcentralized. Fig. 5 shows the turbine spinner response to a combined fit ofdata from monophasic oil and water flow in addition to biphasic flow over awider rate range. These data are for vertical flow. Deviated flow results arecomparable above 5,000 B[D. Fig. 5 also indicates the spinner"efficiency," i.e., the ratio of measured to theoretical response basedon impeller pitch. Flow-loop data illustrate that continuous spinner flowmetersdemonstrate predictable, linear response under high-rate conditions. Atmoderate rates, response depends more heavily on wellbore deviation and watercut. Low flow rates can produce uninterpretable measurements. Therefore, continuous spinners are most effective in testing multilayered reservoirs beingproduced at high rates. Use of such tools for buildup testing of single-layerreservoirs works best in high-rate gas wells, where higher wellbore storageallows better afterflow measurement. SPEPE P. 427
Abstract There are two primary reasons to utilize a flowmeter. One reason is to measure total flow rate at different depths in a well. Total flow is then used for a single phase flow profile or used in conjunction with other sensors to produce a multiphase flow profile. Measurement of transient rate in conjunction with pressure transient testing is another use of the flowmeter. The analysis of these transients then yields reservoir parameters such as permeability, skin, and reservoir pressure. In either case, flow rates must be accurately measured or gross errors in the final interpretation will result. Multiphase flow, especially in deviated wells, often results in an unpredictable flowmeter response. Most wells are multiphase downhole with a high percent of water present even though little or no water is being produced at the surface. This downhole condition makes it difficult to derive an accurate flow rate from a measured spinner speed. Petal basket flowmeters attempt to force fluids into a flow regime that can be measured but fail because all of the flow is not diverted through the metering section. A new flowmeter is described that has a linear, predictable response in single and multiphase flow and results in a much better measurement of downhole flow rates. Flow loop data are presented, comparisons are made of the new flowmeter response with other flowmeter responses and the results of field tests are discussed. Introduction Fluid flow is a complex phenomenon. There are many correlations and models attempting to describe multiphase flow and account for phase velocities, pressure gradients, and flow regimes. Brown and Beggs discusses the methods of several authors in their chapter on "Multiphase Flow in Pipes" as do Hasan and Kabir in their study of flow behavior in vertical wells. Even wells that produce essentially water free at the surface usually have a high water holdup (fraction of water by volume) downhole below tubing. This high water holdup occurs because the velocity of the produced fluids downhole, in normally used casing sizes, is not sufficient to clean water out of the well (less than 1% of the wells in North America produce enough to be monophasic downhole). The multiphase environment can cause anomolous flowmeter readings, a problem that is particularly aggravated in deviated wells. In transient well testing using transient rate and pressure measurements the holdups and velocity profiles are often changing with time. The effect on flowmeters can negatively affect the estimation of reservoir parameters. Flowmeter readings in monophasic wells are also affected by changing velocity profiles. A new device, an inflatable diverter flowmeter tool, has been developed to force the fluids into a flow regime and/or velocity profile that will enable fluid velocity (flow rate) to be measured. SINGLE AND MULTIPHASE FLUID FLOW Fig. 1 shows velocity profiles for laminar and turbulent flow of a single phase fluid. The center velocity for laminar flow may be twice that of the average fluid velocity. Many flowmeter measurements are not only a function of the velocity profile, but are also a function of tool size relative to flowing cross-sectional area, tool centralization, and tool hardware effects on the velocity profile. However, most wells are not single phase downhole. It takes approximately 1000 STB/D of oil or 1,000,000 to 2,000,000 scf/of gas to carry produced water or completion fluids out of 5.5-in. casing or to produce a relatively homogeneous mixture of fluids. The exact number depends on formation volume factors. In most producing wells there is a very high percentage of water present over much, if not all, of the producing interval. This condition occurs even if little or no water is produced at the surface and results in flow regimes such as shown in Fig. 2, or similar regimes representing 3-phase flow. Because of the difference in flowing fluid properties (mainly density, viscosity and interfacial tension), the fluids move at different velocities. The flow regime at a given time is not only dependent on flow rates, but also on fluid properties, pipe size and condition, wellbore deviation, logging tool presence, and proximity of fluid entries. Under these circumstances, it is understood that some flowmeters may not be able to obtain an average fluid velocity. P. 703^
- North America > United States > Texas (0.47)
- North America > United States > California (0.29)
ABSTRACT Compared with the difference between the densities of gas and liquid phases, the difference between the densities of oil and water is insignificant. So flow patterns, slip velocity and the corresponding production log interpretation method differs greatly from the gas/liquid two-phase flow. Considering the characteristics of oil/water two-phase flows and based on the experiment result from flow loop, this paper presents a method to directly identify the flow patterns from production well logs, and a dependable approach is also given to determine slip velocities. Finally the paper points out the similarities and differences among the current production log interpretation methods.
Abstract Downhole flow and pressure measurements monitored in low flow rate gas-lifted wells in multilayer reservoirs offshore West Africa revealed that production from many of these wells was cyclic in nature. This phenomenon, called "slugging", causes bottomhole measurements to oscillate in unstable fashion. The traditional approach used in measuring vertical flow profiles and computing production allocations for the individual zones drained was invalidated as a result. Inflatable Diverter Flowmeters* were used successfully in these low rate/high deviation/high water cut wells to provide measurements which, when interpreted as provide measurements which, when interpreted as discussed in this paper, yielded not only the desired flow profiles but also permeability, skin factor and potential of profiles but also permeability, skin factor and potential of the individual layers that were monitored. The flowmeter's response pattern under these conditions was verified by comparison against a numerical reservoir simulator model currently used for multilayered reservoir interpretation. The extension of this technique to the analysis of unstable wells is discussed. The results from a successful match between simulated and measured data (achieved via nonlinear optimizations) provided the layer permeabilities, skins and potentials which, in turn, were combined to derive synthetic flow profiles and by layer inflow performance curves. Two field examples of wells exhibiting cyclic flow behavior are presented. Results compared favorably with those from buildup tests. Based on experience gained from the evaluation of these wells, recommendations are made for modifying data acquisition schemes so as to enhance final interpretation answers. Introduction Multiphase flow, especially in deviated wells, has proved very difficult to measure particularly if the flow rates are low. In many gas lift wells flow may be unstable, often in a cyclic manner commonly known as slugging in which case traditional profile measurements have been impossible to obtain. Elf Congo made several unsuccessful attempts in 1987 to measure such flow rates in a developed multilayer reservoir. Unstable two phase flow in deviated wells was the cause. The objective of these measurements was to establish a flow profile in the wells in order to assign production contributions to each of the up to 5 layers making up the reservoir. This would establish a more sound basis for decisions on the efficiency of the water injection programme and potential recompletions or workovers. In previous attempts fullbore flowmeters, tracer injection and petal basket flowmeters, were used with little or no success. The Inflatable Diverter Flowmeter (IDF*) service, introduced in 1987 offered a solution. The IDF tool utilizes a fabric diverter with an inflatable outer ring which causes the flowing wellbore fluids to be forced through the metering section of the tool (Fig 1.). The response of this tool in a two phase liquid environment has been found to be linear and insensitive to changes in water cut (Fig. 2). The spinner threshold is of the order of 2.4 m/d (15 bbl/d) and flow up to 320 m/d (2000 bbl/d) can be measured before there is any likelihood that the diverter section ruptures or the pressure differential across the tool becomes too great. P. 371
- Africa (0.68)
- North America > United States > Texas (0.28)
- Reservoir Description and Dynamics (1.00)
- Production and Well Operations > Well & Reservoir Surveillance and Monitoring > Production logging (1.00)
- Production and Well Operations > Well & Reservoir Surveillance and Monitoring > Downhole and wellsite flow metering (1.00)
- Production and Well Operations > Artificial Lift Systems > Gas lift (1.00)
The Well Logging Technology and Application for Fluid Injection and Production Profile in Daqing Oilfield
Xie, Ronghua (Production Well Logging Institute of Daqing Oilfield Company Limited) | Liu, Xingbin (Production Well Logging Institute of Daqing Oilfield Company Limited) | Hou, Yunfu (Production Well Logging Institute of Daqing Oilfield Company Limited)
Abstract At present, Daqing Oilfield is at the stage of oil production with high watercut. As the watercut of fluid produced from oil production wells is increasing higher, the two profile logging data are also progressively required. Alongside the oil recovery technological applications of polymer flooding and ASP flooding, it is more and more difficult to measure the two profiles. In view of this situation, the logging techniques for measuring fluid injection and production profiles used appropriately at the stage of oil production with high watercut and polymer injection flooding are developed. In this paper, these logging technologies and their applications in Daqing Oilfield are introduced. It is mainly with focus on introducing the through casing-tubing annulus logging techniques. The Overview of Production Well Logging in Daqing Oilfield The fluid injection profile and production profile logging data play an important role in an oilfield development. The two profile logs can provide performance data for the geological analysis and offer the data for hydraulic fracturing, acidizing and chemical water shutting off (WSO) treatments in water injection wells and oil production wells, and therefore, the logging data can be also needed for evaluating the operating effects. The logging can be used to monitor developed areas systematically to study the conditions of producing reserves and watered out conditions for adopting an appropriate injection-production plan for increasing production and oil recovery efficiency. Due to the specific geological and developed condition in Daqing Oilfield, the two-profile logging calls for higher demands. Daqing Oilfield is a large non-marine sedimentary reservoir with multisand oil zones, and the output of the oil production well is low and watercut is high. Since most oil wells in the oilfield are pumping well, the production logging tools must be run into wells through casing-tubing annulus, very small diameters of the tools makes it very difficult to measure the flowrate and watercut accurately. In Daqing Oilfield, the oil production is conducted by means of selective injection into individual zones and the injected fluid is flowing into formation behind the water injection mandrels, which makes the conventional contact method can not be used for measuring the water intake profiles at each injection allocation zone. For this reason, the logging technique is difficult to be developed for measuring fluid injection profiles. Daqing Oilfield development is now at the stage of tertiary oil recovery, polymer flooding, three component (polymer, alkli and surfactant) combination flooding (ASP flooding) and foam flooding will be the main measures for improving the oil recovery efficiency. For the fluid injection wells and oil production wells during tertiary oil recovery period, the fluid in a wellbore has non-Newtonian behavior. The flow in the production well flooded by polymer is an oil, gas, water, and polymer four-phase flow, in which the flow characteristic is very complex. Study of the new monitoring techniques for measuring the two profiles of these wells becomes a new problem. For the complex problem faced by the two-profile logging, Daqing Oilfield dispatched a lot of research fellow to develop the two profile logging technology. For the fluid injection profile, the radioisotopic water intake profile logging technology, the continuous spinner flowmeter measuring water intake profile logging technology used in generalized water injection wells, and the electromagnetic flowmeter measuring intake profile in polymer injection and water injection wells have been developed. For the oil production profiles logging, various survey techniques, including through tubing-casing-annulus diverter flowmeter, watercut meters and radioactive densimeter were developed for measuring oil/water two-phase flows and oil/gas/water three phase flows. A large-scale multiphase flow experimental facility was constructed which allows carrying out the flow mechanism investigations, logging tool researches and tool calibrations.
- Asia > China > Heilongjiang > Songliao Basin > Daqing Field > Yian Formation (0.99)
- Asia > China > Heilongjiang > Songliao Basin > Daqing Field > Mingshui Formation (0.99)
- Asia > China > Shandong > North China Basin > Shengli Field (0.94)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Waterflooding (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Chemical flooding methods (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Open hole/cased hole log analysis (1.00)
- Production and Well Operations (1.00)