Production of fines together with reservoir fluid is called solid production. It varies from a few grams or less per ton of reservoir fluid posing only minor problems, to catastrophic amount possibly leading to erosio...Production of fines together with reservoir fluid is called solid production. It varies from a few grams or less per ton of reservoir fluid posing only minor problems, to catastrophic amount possibly leading to erosion and complete filling of the borehole. This paper assesses solid production potential in a carbonate gas reservoir located in the south of Iran. Petrophysical logs obtained from the vertical well were employed to construct mechanical earth model. Then, two failure criteria, i.e. Mohre Coulomb and Mogi-Coulomb,were used to investigate the potential of solid production of the well in the initial and depleted conditions of the reservoir. Using these two criteria, we estimated critical collapse pressure and compared them to the reservoir pressure. Solid production occurs if collapse pressure is greater than pore pressure. Results indicate that the two failure criteria show different estimations of solid production potential of the studied reservoir. Mohre Coulomb failure criterion estimated solid production in both initial and depleted conditions, where Mogi-Coulomb criterion predicted no solid production in the initial condition of reservoir. Based on Mogi-Coulomb criterion, the well may not require completion solutions like perforated liner, until at least 60% of reservoir pressure was depleted which leads to decrease in operation cost and time.展开更多
We present theoretical and experimental studies on the effects of formationproperties on seismoelectric conversions in fluid-filled boreholes. First, we derive thetheoretical formulations for seismoelectric responses ...We present theoretical and experimental studies on the effects of formationproperties on seismoelectric conversions in fluid-filled boreholes. First, we derive thetheoretical formulations for seismoelectric responses for an acoustic source in a borehole.Then, we compute the electric fields in boreholes penetrating formations withdifferent permeability and porosity, and then we analyze the sensitivity of the convertedelectric fields to formation permeability and porosity. We also describe the laboratoryresults of the seismoelectric and seismomagnetic fields induced by an acousticsource in borehole models to confirm our theoretical and numerical developmentsqualitatively. We use a piezoelectric transducer to generate acoustic waves and a pointelectrode to receive the localized seismoelectric fields in layered boreholes and theelectric component of electromagnetic waves in a fractured borehole model. Numericalresults show that the magnitude ratio of the converted electric wave to the acousticpressure increases with the porosity and permeability increases in both fast and slowformations. Furthermore, the converted electric signal is sensitive to the formationpermeability for the same source frequency and formation porosity. Our experimentsvalidate our theoretical results qualitatively. An acoustic wave at a fracture intersectinga borehole induces a radiating electromagnetic wave.展开更多
Pulsed neutron-neutron(PNN)logging is based on emitting neutrons into the near-wellbore zone and computing the neutron count decay due to scattering and capturing.The main application of this logging tool is to determ...Pulsed neutron-neutron(PNN)logging is based on emitting neutrons into the near-wellbore zone and computing the neutron count decay due to scattering and capturing.The main application of this logging tool is to determine the current oil saturation and to detect channeling in perforated and non-perforated intervals behind the casing.Correct interpretation of the results obtained from PNN logging enables engineers to predict new perforation intervals in depleted reservoirs.This study examines the application of PNN logging in a well located in one of Iranian oil reservoirs.The interpretation procedure is described step by step.The principle of the PNN logging and the specifications of the tool are discussed and the applications of PNN logging in evaluation of oil saturation,identification of water flooded zones and prediction of potential perforating zones are described.Channeling is also investigated between all layers,good and poor oil zones are characterized based on the calculated oil saturations and new perforation intervals are suggested with the aim to boost oil production from the reservoir.The results of this study show that zones 1 to 5 having low oil saturations,are interpreted as depleted oil zones.Zones 6 to 8 are interpreted as good oil zones having high potential to produce oil.Zone 9 is interpreted as a water zone.展开更多
Electrofacies are used to determine reservoir rock properties,especially permeability,to simulate fluid flow in porous media.These are determined based on classification of similar logs among different groups of loggi...Electrofacies are used to determine reservoir rock properties,especially permeability,to simulate fluid flow in porous media.These are determined based on classification of similar logs among different groups of logging data.Data classification is accomplished by different statistical analysis such as principal component analysis,cluster analysis and differential analysis.The aim of this study is to predict 3D FZI(flow zone index)and Electrofacies(EFACT)volumes from a large volume of 3D seismic data.This study is divided into two parts.In the first part of the study,in order to make the EFACT model,nuclear magnetic resonance(NMR)log parameters were employed for developing an Electrofacies diagram based on pore size distribution and porosity variations.Then,a graph-based clustering method,known as multi resolution graph-based clustering(MRGC),was employed to classify and obtain the optimum number of Electrofacies.Seismic attribute analysis was then applied to model each relaxation group in order to build the initial 3D model which was used to reach the final model by applying Probabilistic Neural Network(PNN).In the second part of the study,the FZI 3D model was created by multi attributes technique.Then,this model was improved by three different artificial intelligence systems including PNN,multilayer feed-forward network(MLFN)and radial basis function network(RBFN).Finally,models of FZI and EFACT were compared.Results obtained from this study revealed that the two models are in good agreement and PNN method is successful in modeling FZI and EFACT from 3D seismic data for which no Stoneley data or NMR log data are available.Moreover,they may be used to detect hydrocarbon-bearing zones and locate the exact place for producing wells for the future development plans.In addition,the result provides a geologically realistic spatial FZI and reservoir facies distribution which helps to understand the subsurface reservoirs heterogeneities in the study area.展开更多
Hydrocarbon generation from sedimentary organic matter(SOM)with an original net C oxidation state(OS,-1–-2)is a disproportionation reaction involving the transfer of internal(“organic”)hydrogen and producing oxidiz...Hydrocarbon generation from sedimentary organic matter(SOM)with an original net C oxidation state(OS,-1–-2)is a disproportionation reaction involving the transfer of internal(“organic”)hydrogen and producing oxidized C(up to OS=+4)and reduced C(down to OS=-4).The contribution of extrinsic(“inorganic”)hydrogen could lead to an increase of hydrocarbon yields,but mechanisms and potential sources are still unclear,although it is supported by some experimental evidence.In this study,we have analyzed quantitatively the effect of increasing hydrogen fugacity on the hydrocarbon generation behavior of the Cambro-Ordovician Alum shale at 350℃and 40 MPa.Hydrogen fugacity in the experimental system was controlled by the magnetite-hematite(MH)buffer.The experimental data confirm that a more reducing environment will increase overall hydrocarbon yields and depress CO_(2) yields.The elevated hydrogen fugacity was found to correlate with an increase in δ^(13)C isotopic composition of methane and a decrease of δ^(13)C values in CO_(2),ethane and propane.This demonstrates that elevated hydrogen fugacity constrained by water-rock reaction in sedimentary basins can enhance hydrocarbon generation by“hydrocracking”.This mechanism of hydrocarbon generation by organic-inorganic interactions might be ubiquitous in the deeper sections of sedimentary basins(approximately 4–10 km).Thus,it will extend the connotation of the current theory on petroleum generation.The level of hydrogen fugacity,constrained by water-rock reactions,increases with depth and may thus activate over-maturity sedimentary organic matter to produce more hydrocarbons.The end of hydrocarbon generation will thus move to a greater depth than predicted by the traditional theory.It will be correlated to the capacity of the buffer system,which should,in consequence,be taken into account in petroleum exploration,similar to the hydrogen index(HI)of SOM.This extension of the fundamental theory will help to enlarge the area of petroleum exploration to ultra-deep strata in sedimentary basins.展开更多
Borehole acoustic logging-while-drilling (LWD) for formation evaluationhas become an indispensable part of hydrocarbon reservoir assessment [F. Citt ´a, C. Rus-sell, R. Deady and D. Hinz, The Leading Edge, 23 (20...Borehole acoustic logging-while-drilling (LWD) for formation evaluationhas become an indispensable part of hydrocarbon reservoir assessment [F. Citt ´a, C. Rus-sell, R. Deady and D. Hinz, The Leading Edge, 23 (2004), pp. 566-573]. However,the detection of acoustic formation arrivals over tool mode contamination has beena challenging problem in acoustic LWD technology. In this paper we propose a newmethod for separating tool waves from formation acoustic waves in acoustic LWD.This method is to measure the seismoelectric signal excited by the LWD acoustic waves.The LWD tool waves which propagate along the rigid tool rim can not excite any elec-tric signal. This is due to the effectively grounding of the drill string during the LWDprocess makes it impossible to accumulate any excess charge at the conductive tool —borehole fluid interface. Therefore, there should be no contribution by the tool modesto the recorded seismoelectric signals. To theoretically understand the seismoelectricconversion in the LWD geometry, we calculate the synthetic waveforms for the multi-pole LWD seismoelectric signals based on Pride’s theory [S. R. Pride, Phys. Rev. B, 50(1994), pp. 15678-15696]. The synthetic waveforms for the electric field induced by theLWD-acoustic-wave along the borehole wall demonstrate the absence of the tool mode.We also designed the laboratory experiments to collect simulated LWD monopole anddipole acoustic and seismoelectric signals in a borehole in sandstone. By analyzing thespectrum of acoustic and electric signals, we can detect and filter out the differencebetween the two signals, which are the mainly tool modes and noise.展开更多
文摘Production of fines together with reservoir fluid is called solid production. It varies from a few grams or less per ton of reservoir fluid posing only minor problems, to catastrophic amount possibly leading to erosion and complete filling of the borehole. This paper assesses solid production potential in a carbonate gas reservoir located in the south of Iran. Petrophysical logs obtained from the vertical well were employed to construct mechanical earth model. Then, two failure criteria, i.e. Mohre Coulomb and Mogi-Coulomb,were used to investigate the potential of solid production of the well in the initial and depleted conditions of the reservoir. Using these two criteria, we estimated critical collapse pressure and compared them to the reservoir pressure. Solid production occurs if collapse pressure is greater than pore pressure. Results indicate that the two failure criteria show different estimations of solid production potential of the studied reservoir. Mohre Coulomb failure criterion estimated solid production in both initial and depleted conditions, where Mogi-Coulomb criterion predicted no solid production in the initial condition of reservoir. Based on Mogi-Coulomb criterion, the well may not require completion solutions like perforated liner, until at least 60% of reservoir pressure was depleted which leads to decrease in operation cost and time.
文摘We present theoretical and experimental studies on the effects of formationproperties on seismoelectric conversions in fluid-filled boreholes. First, we derive thetheoretical formulations for seismoelectric responses for an acoustic source in a borehole.Then, we compute the electric fields in boreholes penetrating formations withdifferent permeability and porosity, and then we analyze the sensitivity of the convertedelectric fields to formation permeability and porosity. We also describe the laboratoryresults of the seismoelectric and seismomagnetic fields induced by an acousticsource in borehole models to confirm our theoretical and numerical developmentsqualitatively. We use a piezoelectric transducer to generate acoustic waves and a pointelectrode to receive the localized seismoelectric fields in layered boreholes and theelectric component of electromagnetic waves in a fractured borehole model. Numericalresults show that the magnitude ratio of the converted electric wave to the acousticpressure increases with the porosity and permeability increases in both fast and slowformations. Furthermore, the converted electric signal is sensitive to the formationpermeability for the same source frequency and formation porosity. Our experimentsvalidate our theoretical results qualitatively. An acoustic wave at a fracture intersectinga borehole induces a radiating electromagnetic wave.
文摘Pulsed neutron-neutron(PNN)logging is based on emitting neutrons into the near-wellbore zone and computing the neutron count decay due to scattering and capturing.The main application of this logging tool is to determine the current oil saturation and to detect channeling in perforated and non-perforated intervals behind the casing.Correct interpretation of the results obtained from PNN logging enables engineers to predict new perforation intervals in depleted reservoirs.This study examines the application of PNN logging in a well located in one of Iranian oil reservoirs.The interpretation procedure is described step by step.The principle of the PNN logging and the specifications of the tool are discussed and the applications of PNN logging in evaluation of oil saturation,identification of water flooded zones and prediction of potential perforating zones are described.Channeling is also investigated between all layers,good and poor oil zones are characterized based on the calculated oil saturations and new perforation intervals are suggested with the aim to boost oil production from the reservoir.The results of this study show that zones 1 to 5 having low oil saturations,are interpreted as depleted oil zones.Zones 6 to 8 are interpreted as good oil zones having high potential to produce oil.Zone 9 is interpreted as a water zone.
文摘Electrofacies are used to determine reservoir rock properties,especially permeability,to simulate fluid flow in porous media.These are determined based on classification of similar logs among different groups of logging data.Data classification is accomplished by different statistical analysis such as principal component analysis,cluster analysis and differential analysis.The aim of this study is to predict 3D FZI(flow zone index)and Electrofacies(EFACT)volumes from a large volume of 3D seismic data.This study is divided into two parts.In the first part of the study,in order to make the EFACT model,nuclear magnetic resonance(NMR)log parameters were employed for developing an Electrofacies diagram based on pore size distribution and porosity variations.Then,a graph-based clustering method,known as multi resolution graph-based clustering(MRGC),was employed to classify and obtain the optimum number of Electrofacies.Seismic attribute analysis was then applied to model each relaxation group in order to build the initial 3D model which was used to reach the final model by applying Probabilistic Neural Network(PNN).In the second part of the study,the FZI 3D model was created by multi attributes technique.Then,this model was improved by three different artificial intelligence systems including PNN,multilayer feed-forward network(MLFN)and radial basis function network(RBFN).Finally,models of FZI and EFACT were compared.Results obtained from this study revealed that the two models are in good agreement and PNN method is successful in modeling FZI and EFACT from 3D seismic data for which no Stoneley data or NMR log data are available.Moreover,they may be used to detect hydrocarbon-bearing zones and locate the exact place for producing wells for the future development plans.In addition,the result provides a geologically realistic spatial FZI and reservoir facies distribution which helps to understand the subsurface reservoirs heterogeneities in the study area.
基金financially supported by the National Key Research and Development Program of China(Grant No.2017YFC0603102)the Foundation of State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum(Beijing)(Grant No.PRP/indep-3-1715)。
文摘Hydrocarbon generation from sedimentary organic matter(SOM)with an original net C oxidation state(OS,-1–-2)is a disproportionation reaction involving the transfer of internal(“organic”)hydrogen and producing oxidized C(up to OS=+4)and reduced C(down to OS=-4).The contribution of extrinsic(“inorganic”)hydrogen could lead to an increase of hydrocarbon yields,but mechanisms and potential sources are still unclear,although it is supported by some experimental evidence.In this study,we have analyzed quantitatively the effect of increasing hydrogen fugacity on the hydrocarbon generation behavior of the Cambro-Ordovician Alum shale at 350℃and 40 MPa.Hydrogen fugacity in the experimental system was controlled by the magnetite-hematite(MH)buffer.The experimental data confirm that a more reducing environment will increase overall hydrocarbon yields and depress CO_(2) yields.The elevated hydrogen fugacity was found to correlate with an increase in δ^(13)C isotopic composition of methane and a decrease of δ^(13)C values in CO_(2),ethane and propane.This demonstrates that elevated hydrogen fugacity constrained by water-rock reaction in sedimentary basins can enhance hydrocarbon generation by“hydrocracking”.This mechanism of hydrocarbon generation by organic-inorganic interactions might be ubiquitous in the deeper sections of sedimentary basins(approximately 4–10 km).Thus,it will extend the connotation of the current theory on petroleum generation.The level of hydrogen fugacity,constrained by water-rock reactions,increases with depth and may thus activate over-maturity sedimentary organic matter to produce more hydrocarbons.The end of hydrocarbon generation will thus move to a greater depth than predicted by the traditional theory.It will be correlated to the capacity of the buffer system,which should,in consequence,be taken into account in petroleum exploration,similar to the hydrogen index(HI)of SOM.This extension of the fundamental theory will help to enlarge the area of petroleum exploration to ultra-deep strata in sedimentary basins.
文摘Borehole acoustic logging-while-drilling (LWD) for formation evaluationhas become an indispensable part of hydrocarbon reservoir assessment [F. Citt ´a, C. Rus-sell, R. Deady and D. Hinz, The Leading Edge, 23 (2004), pp. 566-573]. However,the detection of acoustic formation arrivals over tool mode contamination has beena challenging problem in acoustic LWD technology. In this paper we propose a newmethod for separating tool waves from formation acoustic waves in acoustic LWD.This method is to measure the seismoelectric signal excited by the LWD acoustic waves.The LWD tool waves which propagate along the rigid tool rim can not excite any elec-tric signal. This is due to the effectively grounding of the drill string during the LWDprocess makes it impossible to accumulate any excess charge at the conductive tool —borehole fluid interface. Therefore, there should be no contribution by the tool modesto the recorded seismoelectric signals. To theoretically understand the seismoelectricconversion in the LWD geometry, we calculate the synthetic waveforms for the multi-pole LWD seismoelectric signals based on Pride’s theory [S. R. Pride, Phys. Rev. B, 50(1994), pp. 15678-15696]. The synthetic waveforms for the electric field induced by theLWD-acoustic-wave along the borehole wall demonstrate the absence of the tool mode.We also designed the laboratory experiments to collect simulated LWD monopole anddipole acoustic and seismoelectric signals in a borehole in sandstone. By analyzing thespectrum of acoustic and electric signals, we can detect and filter out the differencebetween the two signals, which are the mainly tool modes and noise.
