Explicit Determination of Reserves for Variable-Bottomhole-Pressure Conditions in Gas Rate-Transient Analysis

SPE Journal ◽  
2019 ◽  
Vol 25 (01) ◽  
pp. 369-390 ◽  
Author(s):  
Yang Wang ◽  
Luis F. Ayala
Keyword(s):  
Transient Analysis ◽  
Gas Flow ◽  
Hyperbolic Equations ◽  
Analytical Models ◽  
Pvt Properties ◽  
Reservoir Properties ◽  
Rate Transient Analysis ◽  
Straight Line ◽  
Bottomhole Pressure

Summary Current rate-transient-analysis tools for gas wells producing under boundary-dominated-flow (BDF) conditions largely rely on the deployment of the Arps empirical decline models (Arps 1945), or liquid-based analytical models rewritten in terms of pseudofunctions. Recently, Stumpf and Ayala (2016) demonstrated that, contrary to common practice, decline exponents (b) used in Arps’ hyperbolic equations when applied to gas-well analysis can be rigorously estimated before any field-production data are collected. This determination is solely dependent on gas pressure/volume/temperature (PVT) properties and prevailing constant-bottomhole-pressure (BHP) specification for volumetric, single-phase gas-flow conditions. In the study, we extend that work to a more-realistic variable-BHP condition, which is the most common production-specification condition, in terms of the ratio of changing BHP to average reservoir pressure. The decline exponent (b) is thus rederived, and it is shown that under such conditions, variable BHP hyperbolic decline coefficients become solely dependent on fluid PVT properties and take their largest possible magnitude compared with constant-BHP production. Step-by-step analysis procedures are presented that enable explicit and straightforward estimation of original gas in place (OGIP) and other reservoir properties by universal-type-curve and straight-line analysis. Finally, several cases using simulated and field data are discussed in detail to validate the capabilities of the proposed approach.

Analytical Rate-Transient Analysis and Production Performance of Waterflooded Fields with Delayed Injection Support

2021 ◽  
pp. 1-23
Author(s):  
Daniel O'Reilly ◽  
Manouchehr Haghighi ◽  
Mohammad Sayyafzadeh ◽  
Matthew Flett
Keyword(s):  
Steady State ◽  
Transient Analysis ◽  
Water Injection ◽  
Data Interpretation ◽  
Production Performance ◽  
Production Data ◽  
Reservoir Properties ◽  
Two Phase ◽  
Production Forecasting ◽  
Rate Transient Analysis

Summary An approach to the analysis of production data from waterflooded oil fields is proposed in this paper. The method builds on the established techniques of rate-transient analysis (RTA) and extends the analysis period to include the transient- and steady-state effects caused by a water-injection well. This includes the initial rate transient during primary production, the depletion period of boundary-dominated flow (BDF), a transient period after injection starts and diffuses across the reservoir, and the steady-state production that follows. RTA will be applied to immiscible displacement using a graph that can be used to ascertain reservoir properties and evaluate performance aspects of the waterflood. The developed solutions can also be used for accurate and rapid forecasting of all production transience and boundary-dominated behavior at all stages of field life. Rigorous solutions are derived for the transient unit mobility displacement of a reservoir fluid, and for both constant-rate-injection and constant-pressure-injection after a period of reservoir depletion. A simple treatment of two-phase flow is given to extend this to the water/oil-displacement problem. The solutions are analytical and are validated using reservoir simulation and applied to field cases. Individual wells or total fields can be studied with this technique; several examples of both will be given. Practical cases are given for use of the new theory. The equations can be applied to production-data interpretation, production forecasting, injection-water allocation, and for the diagnosis of waterflood-performanceproblems. Correction Note: The y-axis of Fig. 8d was corrected to "Dimensionless Decline Rate Integral, qDdi". No other content was changed.

Rate-Transient Analysis of a Constant-Bottomhole-Pressure Multihorizontal Well Pad with a Semianalytical Single-Phase Method

SPE Journal ◽  
2020 ◽  
Vol 25 (06) ◽  
pp. 3280-3299
Author(s):  
Hongyang Chu ◽  
Xinwei Liao ◽  
Zhiming Chen ◽  
W. John John Lee
Keyword(s):  
Transient Analysis ◽  
Single Phase ◽  
Unconventional Reservoirs ◽  
Phase Method ◽  
Production Data ◽  
Transition Flow ◽  
Well Spacing ◽  
Rate Transient Analysis ◽  
Negative Effect ◽  
Bottomhole Pressure

Summary Because of readily available production data, rate-transient analysis (RTA) is an important method to predict productivity and reserves, and for reservoir and completion characterization in unconventional reservoirs. In addition, multihorizontal well pads are a common development method for unconventional reservoirs. Close well spacing between multifractured horizontal wells (MFHWs) in the multiwell pads makes interference from adjacent MFHWs especially significant. For RTA of production data from multihorizontal well pads, the influence of adjacent MFHWs cannot be ignored. In this work, we propose a semianalytic RTA model for the multihorizontal well pad with arbitrary multiple MFHW properties and starting-production times. Combining Laplace transformation and finite-difference analysis, we obtained a general solution of a multiwell mathematical model to use in RTA. Our model is applicable to cases of multiple MFHWs with different bottomhole pressures (BHPs), varying hydraulic-fracture properties, and different starting-production times. In the solutions, we observe bilinear flow, linear flow, transition flow, and multi-MFHW flow. Rate-normalized pressure (RNP) and its derivative are also affected by multi-MFHW flow. Two case studies revealed that the negative effect of interwell interference on the parent-well productivity is closely related to the pressure distribution caused by the production of child wells.

scholarly journals To Interpret Rate Transient Analysis for the Determination of Reservoir Properties

2019 ◽  
Vol 8 (4) ◽  
pp. 1508-1511
Keyword(s):  
Production Rate ◽  
Transient Analysis ◽  
Transient Flow ◽  
Curve Analysis ◽  
Late Time ◽  
Type Curve ◽  
Rate Transient Analysis ◽  
Decline Curve ◽  
Time Period

Rate-time decline curve analysis is a major technique which is mostly used in petroleum engineering. Many methods are used for the determination of the decrease in the production rate within a given period of time. The main disadvantage of Arp’s decline type curve analysis is that it is only used for boundary dominated flow period; it is not used for transient flow period. The analysis of the Fetkovich is to determine the log-log type curve for both the transient flow period (early time period or infinite) and boundary-dominated flow period (late time period). Arps developed the type curve which shows the production rate decline with time for the finite reservoir or late time period. The exponential or constant flow decline, hyperbolic decline, and harmonic decline according to the value of decline curve exponent (b) is given by Arps. After that Fetkovich improved on earlier work done by Arps in predicting decline production rate of wells over a given period of time. The main objective of this study was to plotting the rate transient analysis curve. I will plot the Fetkovich type curve (combined early and late times region). The graph will be plotted between the dimensionless decline flow rate (qDd) and the dimensionless decline time” (tDd). This will be the objective of the study.

Rigorous and Explicit Determination of Reserves and Hyperbolic Exponents in Gas-Well Decline Analysis

SPE Journal ◽  
2016 ◽  
Vol 21 (05) ◽  
pp. 1843-1857 ◽  
Author(s):  
T. N. Stumpf ◽  
Luis F. Ayala
Keyword(s):  
Hyperbolic Model ◽  
Time Data ◽  
Gas Reservoirs ◽  
Reservoir Properties ◽  
Type Curves ◽  
Reservoir Evaluation ◽  
Straight Line ◽  
Proposed Model ◽  
Fluid Properties

Summary Reservoir evaluation on the basis of rate-time data of gas wells producing under boundary-dominated flow (BDF) is often performed with the Arps’ empirical hyperbolic decline model and associated type curves. In this study, we show that, for volumetric, single-phase, gas reservoirs produced at constant bottomhole pressure, the decline exponent, b, used in Arps’ hyperbolic model can be calculated solely on the basis of fluid properties and the prevailing bottomhole specification—regardless of reservoir properties and before collecting any rate-time data. For the case of real gases produced under less-than wide-open decline, the assumption of a constant b necessary for the use of Arps’ equations does not hold true throughout the production life of a reservoir. We show that during early BDF, a hyperbolic window may be defined for which the constant-b assumption may be valid. Within this window, we show that the application of type-curve and straight-line analysis techniques derived from the hyperbolic model can be used to successfully and explicitly determine reservoir properties, including original gas in place (OGIP). Several case studies based on numerical simulation and field data are presented to thoroughly validate and highlight the predictive capabilities of the proposed model.

Rate transient analysis of fractured horizontal wells

2020 ◽  
pp. 62-67
Author(s):  
R.R. Urazov ◽  
◽  
A.Ya. Davletbaev ◽  
A.I. Sinitskiy ◽  
A.Kh. Nuriev ◽  
...  
Keyword(s):  
Transient Analysis ◽  
Horizontal Wells ◽  
Rate Transient Analysis ◽  
Fractured Horizontal Wells
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