Determination of Reservoir Fluid Properties from Samples Contaminated with Oil Based Mud Filtrate

1998 ◽  
Author(s):  
F. Gozalpour
Keyword(s):  
Reservoir Fluid ◽  
Fluid Properties ◽  
Mud Filtrate

Effect of Dilution on Acoustic and Transport Properties of Reservoir Fluid Systems and Their Interplay

SPE Journal ◽  
2020 ◽  
Vol 25 (06) ◽  
pp. 2867-2880
Author(s):  
Ram R. Ratnakar ◽  
Edward J. Lewis ◽  
Birol Dindoruk
Keyword(s):  
Measurement Techniques ◽  
Saturation Pressure ◽  
Ultrasonic Pulse ◽  
Acoustic Velocity ◽  
Viscosity Data ◽  
Reservoir Fluid ◽  
Fluid Systems ◽  
Fluid Properties ◽  
Volume Measurements ◽  
Live Oil

Summary Acoustic velocity is one of the key thermodynamic properties that can supplement phase behavior or pressure/volume/temperature (PVT) measurements of pure substances and mixtures. Several important fluid properties are relatively difficult to obtain through traditional measurement techniques, correlations, or equation of state (EOS) models. Acoustic measurements offer a simpler method to obtain some of these properties. In this work, we used an experimental method based on ultrasonic pulse-echo measurements in a high-pressure/high-temperature (HP/HT) cell to estimate acoustic velocity in fluid mixtures. We used this technique to estimate related key PVT parameters (such as compressibility), thereby bridging gaps in essential data. In particular, the effect of dilution with methane (CH4) and carbon dioxide (CO2) at pressures from 15 to 62 MPa and temperatures from 313 to 344 K is studied for two reservoir fluid systems to capture the effect of the gas/oil ratio (GOR) and density variations on measured viscosity and acoustic velocity. Correlative analysis of the acoustic velocity and viscosity data were then performed to develop an empirical correlation that is a function of GOR. Such a correlation can be useful for improving the interpretation of the sonic velocity response and the calibration of viscosity changes when areal fluid properties vary with GOR, especially in disequilibrium systems. In addition, under isothermal conditions, the acoustic velocity of a live oil decreases monotonically with decreasing pressure until the saturation point where the trend is reversed. This observation can also be used as a technique to estimate the saturation pressure of a live oil or as a byproduct of the target experiments. It supplements the classical pressure/volume measurements to determine the bubblepoint pressure.

Analytic Determination of Slip and Efficiencies of Rolling Contact C.V.T.’s With Experimental Verifications

1986 ◽  
Vol 108 (1) ◽  
pp. 72-76 ◽  
Author(s):  
J. Modrey ◽  
Y. K. Younes
Keyword(s):  
Computer Simulation ◽  
Rolling Contact ◽  
Analytic Determination ◽  
Continuously Variable Transmissions ◽  
Fluid Properties ◽  
Good Guide ◽  
Parallel Tests

Rolling contact continuously variable transmissions (C.V.T.) transmit forces through a highly viscous spot between rolling-slipping contacts. The mechanics of the spot are characterized by complex elastohydrodynamic conditions and fluid properties only partially determinable at the extreme pressures of operation. A computer simulation of the spot mechanics based on extensions of research in less complex elastohydrodynamic situations was developed. Comparisons with parallel tests on a commercial C. V. T. verify that the simulation described in a good guide to design of this class of transmissions.

Application of Tracers in Oil-Based Mud for Obtaining High-Quality Fluid Composition in Lean Gas/Condensate Reservoirs

2007 ◽  
Vol 10 (01) ◽  
pp. 5-11 ◽  
Author(s):  
Fathollah Gozalpour ◽  
Ali Danesh ◽  
Adrian Christopher Todd ◽  
Bahman Tohidi
Keyword(s):  
Drilling Fluid ◽  
Gas Condensate ◽  
Fluid Composition ◽  
Drilling Process ◽  
Two Fluids ◽  
The North ◽  
Reservoir Fluid ◽  
Partially Miscible ◽  
The North Sea ◽  
Mud Filtrate

Summary Oil-based drilling fluids are used extensively in drilling activities worldwide. During the drilling process, because of overbalance pressure in the mud column, the filtrate of oil-based mud invades the formation. This hydrocarbon-based filtrate mixes with the formation hydrocarbon, which can cause major difficulties in obtaining a representative reservoir-fluid sample. Despite the recent improvements in sampling, obtaining a contamination-free formation fluid is a major challenge, particularly in openhole wells. Depending on the type and conditions of the reservoir, the oil-based-mud filtrate is totally or partially miscible with the formation fluid. Oil-based-mud filtrate dissolves completely in reservoir oil; therefore, the captured sample contains the true reservoir oil with added filtrate. Gas condensate (lean gas condensate in particular) is often not fully miscible with mud filtrate. In this case, the mass exchange between gas condensate and mud filtrate makes the sample unrepresentative of the reservoir fluid. In this study, the impact of sample contamination with oil-based-mud filtrate on different types of reservoir fluids, including gas condensate and volatile-oil samples, is investigated. Two simple methods are suggested to retrieve the uncontaminated composition from a contaminated sample in which mud filtrate is totally dissolved in the formation fluid (i.e., reservoir-oil samples). A tracer-based technique is also developed to determine the composition of an uncontaminated reservoir-fluid sample from a sample contaminated with oil-based-mud filtrate, particularly for those cases in which the two fluids are partially miscible. The tracers are added to the drilling fluid, with the additional cost to the drilling-mud preparation being negligible. The capability of the developed techniques has been examined against deliberately contaminated reservoir-fluid samples under controlled conditions in the laboratory. The results indicate the reliability of the proposed methods. Introduction Historically, most drilling in the North Sea has used water-based muds; however, drilling certain formations with water-based muds can be difficult, primarily because of the hole instability caused by the swelling of water-absorbing rock. Problems of this type can be greatly alleviated by using mud suspended in an oil (rather than water) base. These oil-based muds also provide better lubrication and achieve significant increases in drilling progress (Davies et al. 1984). In recent years, oil-based drilling fluid has been used extensively in drilling activities in the North Sea. During the drilling process, because of overbalance pressure in the mud column, the mud filtrate invades the reservoir formation. Using an oil-based mud in the drilling, the mud filtrate can mix with the formation fluid. This can cause major difficulties in obtaining high-quality formation-fluid samples. Depending on the type and conditions of the reservoir, the mud filtrate can be totally or partially miscible with the formation fluid. This can alter the composition and phase behavior of the reservoir fluid significantly. Hence, the measured data using the collected formation-fluid samples need to be corrected for the contamination. In this study, contamination of different types of reservoir fluids with oil-based-mud filtrate, where the two fluids are partially or totally miscible, is discussed. Practical decontamination techniques are proposed to retrieve the original fluid composition from contaminated samples.

A Sensitivity Study of Reservoir Performance Using a Compositional Reservoir Simulator

1972 ◽  
Vol 12 (01) ◽  
pp. 3-12
Author(s):  
Edward T.S. Huang
Keyword(s):  
Limited Range ◽  
Measured Data ◽  
Compositional Variation ◽  
Fluid Sample ◽  
Laboratory Measurements ◽  
Reservoir Performance ◽  
Reservoir Fluid ◽  
Liquid Phases ◽  
Fluid Properties ◽  
Compositional Simulator

Abstract Simulation of isothermal fluid flow in a reservoir using a compositional simulator requires fluid properties that are functions of pressure and properties that are functions of pressure and composition. These properties, i.e., K-values, densities and viscosities of both vapor and liquid phases, are usually obtained from general correlations phases, are usually obtained from general correlations or laboratory measurements of a reservoir fluid sample during a differential-depletion experiment in a PVT cell. prediction of fluid properties of complex mixtures using existing correlations is generally subject to great uncertainties. The laboratory measured data that are generally correlated as functions of pressure have validity only over a limited range of compositional variation. The purposes of this paper were (1) to assess, using a linear compositional simulator, the error introduced into calculated reservoir performance by employing fluids with a given range of uncertainties in their physical properties; and (2) to examine the validity of using the physical data correlated in the compositional simulator as functions of pressure rather than functions of both pressure and composition. The gas cycling process was chosen for illustration because composition changes during this process are large and results are affected more than in a depletion-type process. The hypothetical reservoir fluid system considered in this study was a methane-n-butane-n-decane mixture chosen to simulate a volatile oil system. The results of this investigation show for the particular system studied that:(1)the K-values for particular system studied that:(1)the K-values for the lighter components have the most significant effect on the calculated reservoir performance; and(2)simulations using fluid properties that are equivalent to the data measured during a differential depletion experiment reliably predict reservoir performance even under conditions where significant performance even under conditions where significant variations in reservoir fluid composition occur. Introduction A number of papers have recently been published concerning the development of compositional reservoir simulators-the mathematical models that simulate isothermal flow of multiphase, multicomponent fluids in porous media considering mass transfer effects. These models, which properly describe the distribution of each individual component in both vapor and liquid phases and account for pressure and compositional dependence of K-values, phase densities and viscosities, are more rigorous than the conventional simulators. The latter assumes that the heavy component does not exist in the vapor phase. To use the compositional simulator, it is highly desirable that fluid properties, i.e., K-values, densities and viscosities, as functions of pressure and composition, be available. However, for complex reservoir fluid mixtures, this information is rarely available. These fluid properties are usually calculated from published generalized correlations or obtained from laboratory measurements of a reservoir fluid sample by performing differential depletion experiments in a PVT cell. Prediction of fluid properties of complex mixtures using existing correlations is generally subject to great uncertainty. These errors will certainly have effects on the predicted reservoir performance. These effects may predicted reservoir performance. These effects may even be amplified if all the fluid properties are calculated from correlations. Improvement of the correlation predicted data by adjusting these data to match the limited available experimental values for the system of interest can be make. Yet there is no guarantee that the adjusted data will describe reliable fluid behavior in the region away from the matched points. On the other hand, the laboratory measured data, which are expressed as functions of pressure only, have validity over a limited range of pressure only, have validity over a limited range of compositional variation. When compositions of reservoir fluids vary significantly, the reliability of applying the laboratory measured data in the numerical simulation becomes questionable. SPEJ p. 3

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