Fracturing Evaluation for Fractured-Caved Carbonate Reservoirs through Pressure Transient Analysis and Rate Transient Analysis

2016 ◽  
Author(s):  
Yong Li ◽  
Qi Wang ◽  
Baozhu Li ◽  
Xingliang Deng ◽  
Zhicheng She ◽  
...  
Keyword(s):  
Transient Analysis ◽  
Carbonate Reservoirs ◽  
Pressure Transient Analysis ◽  
Pressure Transient ◽  
Rate Transient Analysis

Pressure Transient Analysis for Fracture-Cavity Carbonate Reservoirs with Large Scale Fractures-Caves in Series Connection

2021 ◽  
pp. 1-20
Author(s):  
Cuiqiao Xing ◽  
Hongjun Yin ◽  
Hongfei Yuan ◽  
Jing Fu ◽  
Guohan Xu
Keyword(s):  
Transient Analysis ◽  
Carbonate Reservoir ◽  
Carbonate Reservoirs ◽  
Test Model ◽  
Well Test ◽  
Analysis Model ◽  
Pressure Transient Analysis ◽  
Linear Flow ◽  
Pressure Transient ◽  
Well Test Model

Abstract Fractured vuggy carbonate reservoirs are highly heterogeneous and non-continuous, and contains not only erosion pores and fractures but also the vugs. Unfortunately, the current well test model cannot be used to analyze fractured-vuggy carbonate reservoirs, due to the limitations of actual geological characteristics. To solve the above-mentioned problem, a pressure transient analysis model for fracture-cavity carbonate reservoir with radial composite reservoir that the series multi-sacle fractures and caves exist and dual-porosity medium (fracture and erosion pore) is established in this paper, which is suitable for fractured vuggy reservoirs. Laplace transformation is used to alter and solve the mathematical model. The main fractures' linear flow and the radial flow of caves drainage area are solved by coupling. The pressure-transient curves of the bottomhole have been obtained with the numerical inversion algorithms. The typical curves for well test model which has been established are drawn, and flow periods are analyzed. The sensitivity analysis for different parameters is analyzed. The variation characteristic of typical curves is by the theoretical analysis. With the increasing of fracture length, the time of linear flow is increased. While the cave radius is the bigger, the convex and concave of the curve is the larger. As a field example, actual test data is analyzed by the established model. An efficient well test analysis model is developed, and it can be used to interpret the actual pressure data for fracture-cavity carbonate reservoirs.

scholarly journals Pressure transient analysis of a vertical well with multiple etched fractures in carbonate reservoirs

2019 ◽  
Vol 38 (3) ◽  
pp. 591-612 ◽  
Author(s):  
Erhui Luo ◽  
Yongle Hu ◽  
Zifei Fan ◽  
Wenqi Zhao ◽  
Chenggang Wang ◽  
...  
Keyword(s):  
Transient Analysis ◽  
Carbonate Reservoirs ◽  
Production Performance ◽  
Natural Fracture ◽  
Transitional Flow ◽  
Integral Approach ◽  
Pressure Transient Analysis ◽  
Pressure Transient ◽  
Vertical Well ◽  
Matrix Blocks

Acid fracturing has been widely used as an industry practice in explored and developed carbonate reservoirs. It is very important to understand responses of reservoirs and improve production performance of a well due to the presence of fracture networks by stimulation treatments. Pressure transient analysis is one of the most effective diagnostic techniques available to enhance our understanding of natural and artificial-etched fracture behavior. This work presented a novel mathematical model for unsteady state flow of naturally fractured porous medium into multiple etched fractures intersecting a vertical well, and three different geometric shapes of matrix blocks containing slabs, cylinders and spheres were considered. The new solution was derived by using the Laplace transformation and the point source function integral approach. The polar coordinate transformation was used to deal with the radial distribution of arbitrary fracture number and angle. Then the model was validated by comparison with three published cases. Finally, type curves were plotted to identify flow regimes: linear flow, transitional flow, pseudoradial flow, and boundary dominant flow if the closed or constant pressure boundary exists. Furthermore, sensitivity analysis was investigated. The results showed that the acid-etched fracture parameters containing fracture number, fracture distribution and conductivity had a significant impact on pressure behavior at early times. However, natural fracture storativity coefficient and interporosity flow parameter mainly affected the transitional flow at intermediate times. Moreover, the shape of matrix blocks had a little influence on transient responses at intermediate times. It is found that multiple etched fractures existing near the wellbore consume less pressure drop and increase the productivity of a well as a whole.

Investigation of permeability change in the Bandanna Coal Formation of the Fairview Field using time-lapse pressure transient analysis

2019 ◽  
Vol 59 (1) ◽  
pp. 289 ◽  
Author(s):  
A. Salmachi ◽  
J. Barkla
Keyword(s):  
High Resolution ◽  
Transient Analysis ◽  
Time Lapse ◽  
Production Performance ◽  
Reservoir Pressure ◽  
Permeability Change ◽  
Pressure Transient Analysis ◽  
Pressure Transient ◽  
Coal Permeability ◽  
Rate Transient Analysis

Permeability of coal seam gas (CSG) reservoirs is stress/desorption dependent and may change during the life of the reservoir. This study investigates permeability change with depletion in several CSG wells in the Fairview Field: a prolific reservoir in the Bowen Basin, Australia. High-resolution pressure gauges at surface provide an opportunity to conduct time-lapse pressure transient analysis (PTA) on the wells that have multiple shut-ins. Pressure build-up tests can be replicated by calculating bottom-hole pressure when surface pressure (tubing and/or annulus) is recorded at high-resolution during any shut-in event. This eliminates the need to perform multiple well tests, which are time consuming and costly to run. The production history of 100 CSG wells was examined to find suitable candidates to perform time-lapse PTA. This was used to investigate how Bandanna Coal permeability changes with depletion. Three wells with high-quality shut-ins were identified and analysed to calculate effective permeability to gas and average reservoir pressure. The results indicate that coal permeability can enhance up to one order of magnitude during the life of a CSG well in the Fairview Field, and this can significantly improve production performance. These wells, located in a depleted area of the field, show rapid increase in permeability with decline in average reservoir pressure. The integration of rate transient analysis with the results of time-lapse PTA for one of the study wells reveals that the functional form of permeability increase is exponential in the study area, and a permeability modulus of –0.00678 psia–1 was obtained.

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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