scholarly journals A Practical Methodology for Production Data Analysis in Carbonate Reservoirs Using New Decline Type Curves

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-17
Author(s):  
Zhihao Jia ◽  
Linsong Cheng ◽  
Peng Wang ◽  
Suran Wang ◽  
Pin Jia
Keyword(s):  
Data Analysis ◽  
Carbonate Reservoirs ◽  
Flow Coefficient ◽  
Production Performance ◽  
External Boundary ◽  
Production Data ◽  
Test Interpretation ◽  
Well Test ◽  
Type Curves ◽  
Skin Factor

Carbonate reservoirs typically have complex pore structures, so the production wells typically have high production in the early production stage, but they decline rapidly. It is highly challenging to achieve accurate interpretation results. In this paper, a new and practical methodology for production data analysis of fractured and fractured-vuggy carbonate reservoirs is proposed. Firstly, analytical solutions to characterize the different multipore media and simulate transient production behavior of fractured and fractured-vuggy carbonate reservoirs during the transient flow regime are presented. Then, a new function f q D and f ′ q D that related to the dimensionless production rate is introduced, and a series of new decline type curves are drawn to make a clear observation of different flow regimes. In addition, the effects of the storativity ratio, interporosity flow coefficient, skin factor, and dimensionless radial distance of external boundary on production performance are also analyzed. Finally, two example wells from the fractured and fractured-vuggy carbonate reservoirs are used to perform rate decline analysis with both the Blasingame type curves and the new type curves. The validation of the new method is demonstrated in comparison to the results of well test interpretation. The results show that the curves of 1 / f ′ q D vs. t D are ∧ -shaped for dual-porosity reservoirs and M -shaped for triple porosity reservoirs and also indicate that the interpreted parameters such as permeability, skin factor, storativity ratio, and interporosity flow coefficient using new decline type curves are aligned well test interpretation. In correlation with other traditional well test analysis, this approach effectively reduces the multisolution probability of interpretation.

Comprehensive Well Test Interpretation Method, Process, and Multiple Solutions Analysis for Complicated Carbonate Reservoirs

2019 ◽  
Vol 141 (12) ◽  
Author(s):  
Renfeng Yang ◽  
Ruizhong Jiang ◽  
Shirish Patil ◽  
Shun Liu ◽  
Yihua Gao ◽  
...  
Keyword(s):  
Evaluation Method ◽  
Carbonate Reservoir ◽  
Carbonate Reservoirs ◽  
Production Performance ◽  
Physical Parameters ◽  
Test Interpretation ◽  
Well Test ◽  
Pressure Derivative ◽  
Fracture Characteristics ◽  
Parameter Evaluation

Abstract The main characteristic of the complicated carbonate reservoirs is notably strong heterogeneous, leading to a high uncertainty in formation parameter evaluation. The most reliable method for obtaining the dynamic parameters is well test interpretation. However, the well test curve shows similar characteristics for multi-layers reservoirs, dual-medium reservoirs, and carbonate reservoirs with lithology mixed sedimentation lithology. Sometimes the well test fitting result under the mentioned three kinds of models is satisfied, but the interpretation result is quite different. In order to reduce the parameter evaluation multiplicity, the synthetic identification and evaluation method for obtaining the physical parameters of the complicated carbonate reservoir was proposed, based on completion types, core analysis, lithology analysis, and well test results. The evaluation method distinguishes the different carbonate reservoir characteristics from similar well test responses by summarizing and classifying the completion method, reservoir fracture characteristics, and production logging test (PLT) results. The reliability of the proposed method is verified by an application of actual carbonate reservoir parameters evaluation. The proposed method can distinguish among multi-layers reservoirs, dual-medium, and complicated reservoirs with mixed sedimentation lithology whose main characteristic is that concavity existing in the pressure derivative curve. If the well test match results were satisfied enough which lead to the proposed method and process was ignored, the interpretation results and production performance prediction may deviate largely from the actual situation.

Model Selection for Well Test and Production Data Analysis

1988 ◽  
Vol 3 (01) ◽  
pp. 215-221 ◽  
Author(s):  
A.T. Watson ◽  
J.M. Gatens ◽  
H.S. Lane
Keyword(s):  
Data Analysis ◽  
Model Selection ◽  
Production Data ◽  
Well Test ◽  
Selection For

Gas-Production-Data Analysis of Variable-Pressure-Drawdown/Variable-Rate Systems: A Density-Based Approach

2014 ◽  
Vol 17 (04) ◽  
pp. 520-529 ◽  
Author(s):  
Miao Zhang ◽  
Luis F. Ayala H.
Keyword(s):  
Data Analysis ◽  
Material Balance ◽  
Gas Production ◽  
Variable Pressure ◽  
Production Data ◽  
Variable Rate ◽  
Well Performance ◽  
Gas Well ◽  
Type Curves ◽  
Performance Forecasting

Summary This study demonstrates that production-data analysis of variable-bottomhole-flowing-pressure/variable-rate gas wells under boundary-dominated flow (BDF) is possible by use of a density-based approach. In this approach, governing equations are expressed in terms of density variables and dimensionless viscosity/compressibility ratios. Previously, the methodology was successfully used to derive rescaled exponential models for gas-rate-decline analysis of wells primarily producing at constant bottomhole pressure (Ayala and Ye 2013a, b; Ayala and Zhang 2013; Ye and Ayala 2013; Zhang and Ayala 2014). For the case of natural-gas systems experiencing BDF, gas-well-performance analysis has been made largely possible by invoking the concepts of pseudotime, normalized pseudotime, or material-balance pseudotime. The density-based methodology rigorously derived in this study, however, does not use any type of pseudotime calculations, even for variable-rate/variable-pressure-drawdown cases. The methodology enables straightforward original-gas-in-place calculations and gas-well-performance forecasting by means of type curves or straight-line analysis. A number of field and numerical case studies are presented to showcase the capabilities of the proposed approach.

Production-Data Analysis—Challenges, Pitfalls, Diagnostics

2010 ◽  
Vol 13 (03) ◽  
pp. 538-552 ◽  
Author(s):  
D.. Ilk ◽  
D.M.. M. Anderson ◽  
G.W.J.. W.J. Stotts ◽  
L.. Mattar ◽  
T.A.. A. Blasingame
Keyword(s):  
Data Analysis ◽  
Transient Flow ◽  
Diagnostic Methods ◽  
Production Performance ◽  
Production Data ◽  
Finite Conductivity ◽  
Reservoir Model ◽  
Pressure Transient ◽  
Reservoir Condition ◽  
Wide Range

Summary The analysis of production data to determine reservoir characteristics, completion effectiveness, and hydrocarbons in place has become very popular in recent years. Although production analysis (PA) for reservoir characterization is approaching the popularity of pressure-transient analysis (PTA), there are few consistent diagnostic methods in practice for the analysis of production data. Many of the diagnostic methods for production-data analysis are little more than observation-based approaches—and some are essentially rules of thumb. In this work, we provide guidelines for the analysis of production data, as well as identify common pitfalls and challenges. Although PTA and production-data analyses have the same governing theory (and solutions), we must recognize that pressure transient data are acquired as part of a controlled experiment, performed as a specific event [e.g., a pressure-buildup (PBU) test]. In contrast, production data are generally considered to be surveillance/monitoring data—with little control and considerable variance occurring during the acquisition of the production data. We note that since both PA and PTA have the same governing relations, it is possible "in theory" that the same deliverables of PTA can be obtained using PA. This paper attempts to provide a state-of-the-technology review of current production-data-analysis techniques/tools—particularly tools to diagnose the reservoir model and assess the reservoir condition. The reservoir model is diagnosed mainly by examining the character exhibited by the data [that is the evidence of transient flow (e.g., quarter-slope might indicate a finite-conductivity fracture, or half-slope might indicate radial/pseudoradial flow)]. In addition, one can also assess the reservoir condition by inspecting the character of production data, which can confirm the evidence of boundary-dominated flow such that unit slope may indicate the boundary-dominated-flow regime and, therefore, in-place fluid volume can be estimated. This work also identifies the challenges and pitfalls of PA—and we try to provide guidance toward best practices and best tools. To complement this mission, we use relevant field examples to address specific issues, and we illustrate the value and function of production-data analysis for a wide range of reservoir types and properties. In this work, we propose the use of a sequence of raw and enhanced data plots for the diagnostic analysis of production data. We strongly believe that a comprehensive and systematic approach for production-data diagnosis has significant importance for the analysis and forecast of production performance.

scholarly journals Parameters evaluation of fault-karst carbonate reservoirs with vertical beads-on-string structure based on bottom-hole pressure: Case studies in Shunbei Oilfield, Tarim Basin of Northwestern China

2021 ◽  
Vol 76 ◽  
pp. 59
Author(s):  
Cao Wei ◽  
Shiqing Cheng ◽  
Gang Chen ◽  
Wenyang Shi ◽  
Jiaxin Wu ◽  
...  
Keyword(s):  
Physical Model ◽  
Tarim Basin ◽  
Flow Regimes ◽  
Carbonate Reservoirs ◽  
Gravity Effect ◽  
Well Test ◽  
Pressure Derivative ◽  
Type Curves ◽  
Unit Slope ◽  
String Structure

Tarim Basin newly discovered the fault-karst carbonate reservoirs, which are formed by the large-scale tectonic fault activities and multiple-stage karstification. Four kinds of mediums coexist in the reservoirs, including the large cave, vug, tectonic fracture and matrix. The tectonic fractures interconnect with large caves in series to form the vertical beads-on-string structure, which is the most common connection pattern in reservoirs. To provide a well test method for evaluating this type of structure, this work firstly presents a multi-fracture-region multi-cave-region series connection physical model by simplifying vertical beads-on-string structure. We consider four kinds of mediums in the proposed physical model, including large caves, small vugs, high-angle tectonic fracture and rock matrix. The fracture regions mainly contain fracture, vug and matrix mediums. The cave regions contain cave medium. The corresponding mathematical model is also developed, in which the flow in fracture regions obeys the Darcy’s law, while the flow in cave regions is assumed to obey free flow. Furthermore, the gravity is taken into account because the flow is along the vertical direction. Then the typical flow regimes are analyzed and sensitivity analysis is conducted on crucial parameters. Results indicate that (a) the typical feature of vertical beads-on-string structure on type curves is that the cave storage regimes and linear flow regimes alternately appear; (b) the type curves will exhibit the cave storage regimes with unit-slope pressure derivative for the existence of large caves, which is different from the inter-porosity flow regimes for the existence of the vugs (slope ≠ 1); (c) the gravity effect could lead to unit-slope pressure and pressure derivative curves, which can be regarded as closed boundary in a peculiar sense; (d) gravity effect is difficult to be observed from well test curves with about 2-weeks test duration in real application. Finally, two cases from Shunbei Oilfield are interpreted to illustrate the practicability and feasibility of proposed method.

scholarly journals Pressure Transient Analysis for a Horizontal Well in Heterogeneous Carbonate Reservoirs Using a Linear Composite Model

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Yong-Gang Duan ◽  
Ke-Yi Ren ◽  
Quan-Tang Fang ◽  
Ming-Qiang Wei ◽  
Morteza Dejam ◽  
...  
Keyword(s):  
Transient Analysis ◽  
Horizontal Well ◽  
Flow System ◽  
Carbonate Reservoirs ◽  
Dual Porosity ◽  
Well Test ◽  
Rock Matrix ◽  
Pressure Transient Analysis ◽  
Pressure Transient ◽  
Type Curves

Carbonate reservoirs usually have strong anisotropy. Oil and gas recovery from fractured reservoirs is highly challenging due to complicated mechanisms involved in production from these reservoirs. A horizontal well completed in these reservoirs may extend through multiple zones, including homogeneous, dual-porosity, and triple-porosity formations. Traditional well test models assume that the entire length of a horizontal or multilateral well remains in the same formation with uniform properties. A well test model for pressure transient analysis of horizontal wells extending through a carbonate reservoir consisting of natural fractures, rock matrix, and vugs with different properties is presented in this study. The focus of this study is on dual-porosity (fracture-matrix) and triple-porosity (fracture-matrix-vug) reservoirs, considering the pseudosteady interporosity flows from rock matrix and vugs into fractures. A multizone triple-porosity model was established and solved by using the point source function, Green’s function, and coupling of multiple reservoir sections. The corresponding type curves were developed, and sensitivity analysis was carried out. The type curves of flow stage division reveal that a horizontal well traversing a three-section reservoir including homogeneous, dual-porosity (fracture-matrix)/triple-porosity (fracture-vug-matrix), and homogeneous sections identifies the stages of pseudosteady interporosity flow from matrix and vug into fracture, fracture pseudoradial flow, system linear flow, system pseudoradial flow, and pseudosteady flow occur in sequence. The greater the difference of permeability between the dual-porosity/triple-porosity section and the two homogeneous sections, the more obvious the interporosity flow on the pressure derivative curve. This approach satisfies the need for pressure transient analysis for a horizontal well that traverses two or more regions with distinct properties in heterogeneous carbonate reservoirs.

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