A Simplified and Efficient Method for Water Flooding Production Index Calculations in Low Permeable Fractured Reservoir

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Shun Liu ◽  
Liming Zhang ◽  
Kai Zhang ◽  
Jianren Zhou ◽  
Heng He ◽  
...  
Keyword(s):  
Fractured Reservoirs ◽  
Water Injection ◽  
Cross Flow ◽  
Production Performance ◽  
Water Flooding ◽  
Simplified Model ◽  
Single Fracture ◽  
Fractured Reservoir ◽  
Production Index ◽  
Future Production

Presently, predicting the production performance of fractured reservoirs is often challenging because of the following two factors: one factor such as complicatedly connected and random distribution nature of the fractures and the other factor includes the limitations of the understanding of reservoir geology, deficient fracture-related research, and defective simulators. To overcome the difficulties of simulating and predicting fractured reservoir under complex circumstances of cross flow, a simplified model, which assumes cross flow only exists in the oil phase segment, is constructed. In the model, the pressure distribution of a single fracture can be described by solving an analytical mathematical model. In addition, due to research and field experience which indicate that cross flow also exists in the mixed-phase segment after water injection, the simplified model is modified to consider cross flow in the whole phase. The model constructed here is applicable for fractured reservoirs especially for a low-permeability fracture reservoir, and it moderately predicts future production index. By using iterative methods, the solution to the model can be feasibly obtained and related production performance index formulas can be derived explicitly. A case study was performed to test the model, and the results prove that it is good.

A Mathematical Model for Natural Fracture Evolution in Water-Flooding Oil Reservoir

2013 ◽  
Vol 868 ◽  
pp. 535-541
Author(s):  
Hong Liu ◽  
Lin Wang ◽  
Yu Wu Zhou ◽  
Xi Nan Yu
Keyword(s):  
Oil Recovery ◽  
Rock Fracture ◽  
Fractured Reservoirs ◽  
Water Injection ◽  
Injection Pressure ◽  
Natural Fracture ◽  
Water Flooding ◽  
Oil Well ◽  
Fractured Reservoir ◽  
Naturally Fractured

The fractured low permeability reservoirs develop complex fracture network. As the of waterflooding recovery heightens, excessive high injection pressures and excessive water injection rate will result in open, initiation, propagation and coalescence of micro-fracture, connecting injection with production form the high permeability zone, which results in a one-way onrush of waterflooding, water cut in oil well water rise quickly, causing a severe oil well flooding and channeling, thereby reducing the ultimate oil recovery efficiency. The effect of the waterflooding seepage within natural fracture on fracture initiation is studied and analyzed here, applying the theory of rock fracture mechanics to analyze the interaction of fracture system for naturally fractured reservoirs in waterflooding developing process, studying the mechanical mechanism of opening, initiation, propagation and coalescence of natural fracture under injection pressure, which is important theoretical significance for studying the distribution law of fracture and defining appreciate water injection mode and injection pressure in the process of injection development of the naturally fractured reservoir and for delaying the directivity water break-through and water flooding rate of oil well in the process of injection development.

Forecasting the Water Flooding for the Production Wells of a Gas Condensate Field with a Fractured Reservoir Type

2021 ◽  
Author(s):  
Pavel Dmitrievich Gladkov ◽  
Anastasiia Vladimirovna Zheltikova
Keyword(s):  
Produced Water ◽  
Fractured Reservoirs ◽  
Gas Condensate ◽  
Water Flooding ◽  
Fractured Reservoir ◽  
Well Performance ◽  
Integrated Monitoring ◽  
Field Development ◽  
Water Gas ◽  
Gas Ratio

Abstract As is known, fractured reservoirs compared to conventional reservoirs have such features as complex pore volume structure, high heterogeneity of the porosity and permeability properties etc. Apart from this, the productivity of a specific well is defined above all by the number of natural fractures penetrated by the wellbore and their properties. Development of fractured reservoirs is associated with a number of issues, one of which is related to uneven and accelerated water flooding due to water breakthrough through fractures to the wellbores, for this reason it becomes difficult to forecast the well performance. Under conditions of lack of information on the reservoir structure and aquifer activity, the 3D digital models of the field generated using the hydrodynamic simulators may feature insufficient predictive capability. However, forecasting of breakthroughs is important in terms of generating reliable HC and water production profiles and decision-making on reservoir management and field facilities for produced water treatment. Identification of possible sources of water flooding and planning of individual parameters of production well operation for the purpose of extending the water-free operation period play significant role in the development of these reservoirs. The purpose of this study is to describe the results of the hydrochemical monitoring to forecast the water flooding of the wells that penetrated a fractured reservoir on the example of a gas condensate field in Bolivia. The study contains data on the field development status and associated difficulties and uncertainties. The initial data were results of monthly analyses of the produced water and the water-gas ratio dynamics that were analyzed and compared to the data on the analogue fields. The data analysis demonstrated that first signs of water flooding for the wells of the field under study may be diagnosed through the monitoring of the produced water mineralization - the water-gas ratio (WGR) increase is preceded by the mineralization increase that may be observed approximately a month earlier. However, the data on the analogue fields shows that this period may be longer – from few months to two years. Thus, the hydrochemical method within integrated monitoring of development of a field with a fractured reservoir could be one of the efficient methods to timely adjust the well operation parameters and may extend the water-free period of its operation.

scholarly journals Experimental Study on Enhanced Oil Recovery by Nitrogen-Water Alternative Injection in Reservoir with Natural Fractures

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Xiang Li ◽  
Yuan Cheng ◽  
Wulong Tao ◽  
Shalake Sarulicaoketi ◽  
Xuhui Ji ◽  
...  
Keyword(s):  
Oil Recovery ◽  
Gas Injection ◽  
Water Injection ◽  
Injection Pressure ◽  
Injection Rate ◽  
Water Flooding ◽  
Orthogonal Experimental Design ◽  
Fractured Reservoir ◽  
Natural Fractures ◽  
Nitrogen Injection

The production of a low permeability reservoir decreases rapidly by depletion development, and it needs to supplement formation energy to obtain stable production. Common energy supplement methods include water injection and gas injection. Nitrogen injection is an economic and effective development method for specific reservoir types. In order to study the feasibility and reasonable injection parameters of nitrogen injection development of fractured reservoir, this paper uses long cores to carry out displacement experiment. Firstly, the effects of water injection and nitrogen injection development of a fractured reservoir are compared through experiments to demonstrate the feasibility of nitrogen injection development of the fractured reservoir. Secondly, the effects of gas-water alternate displacement after water drive and gas-water alternate displacement after gas drive are compared through experiments to study the situation of water injection or gas injection development. Finally, the reasonable parameters of nitrogen gas-water alternate injection are optimized by orthogonal experimental design. Results show that nitrogen injection can effectively enhance oil production of the reservoir with natural fractures in early periods, but gas channeling easily occurs in continuous nitrogen flooding. After water flooding, gas-water alternate flooding can effectively reduce the injection pressure and improve the reservoir recovery, but the time of gas-water alternate injection cannot be too late. It is revealed that the factors influencing the nitrogen-water alternative effect are sorted from large to small as follows: cycle injected volume, nitrogen and water slug ratio, and injection rate. The optimal cycle injected volume is around 1 PV, the nitrogen and water slug ratio is between 1 and 2, and the injection rate is between 0.1 and 0.2 mL/min.

scholarly journals Investigation of acid pre-flushing and pH-sensitive microgel injection in fractured carbonate rocks for conformance control purposes

2020 ◽  
Vol 75 ◽  
pp. 52
Author(s):  
Alireza Teimouri ◽  
Saeid Sadeghnejad ◽  
Amir Hossein Saeedi Dehaghani
Keyword(s):  
Flow Rate ◽  
Control Method ◽  
Fractured Reservoirs ◽  
Water Injection ◽  
Ph Sensitive ◽  
Water Flooding ◽  
Fracture Aperture ◽  
Visual Cell ◽  
Conformance Control ◽  
Fractured Carbonate

Waterflooding in fractured reservoirs is a challenging task due to the presence of high conductive flow pathways such as fractures. Much of the injected water passes through fractures without sweeping the oil in the low permeable area, which results in an early breakthrough. Implementing deep conformance control techniques can be a remedy for this early water breakthrough. pH-sensitive microgel injection is a conformance control method in which the dependency of microgel viscosity to pH guarantees easy injection of these microgels into formations at low pH environments. Because of the geochemical reactions among rock minerals, microgels, and a pre-flushing acid, the microgel pH increases; therefore, these microgels swell and block high conductive fractures. In this study, a designed visual cell containing rock samples is implemented to observe rock–microgel interactions during a pH-sensitive microgel flooding into a fractured carbonate medium. First, the dependency of fracture aperture changes to the acid pre-flush flow rate is examined. Then, we investigate the effect of pH-sensitive microgel concentration on its resistance to block fractures during post-water flooding by studying the gel failure mechanisms (e.g., adhesive separation, cohesive failure). Finally, the effect of an initial aperture of fracture is examined on microgel washout when water injection is resumed. The results showed that both decreasing the acid flow rate and lowering the initial aperture could increase the rate of aperture changes. Moreover, the microgel solution with a concentration of 1 wt% showed the highest resistance (98.2 psi/ft) against post-water injection. Additionally, this microgel concentration had the highest permeability reduction factor. Meanwhile, the smaller initial aperture of fracture contributed to a higher microgel resistance.

scholarly journals A New Methodology for the Multilayer Tight Oil Reservoir Water Injection Efficiency Evaluation and Real-Time Optimization

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-17
Author(s):  
Lin Cao ◽  
Jianlong Xiu ◽  
Hongjie Cheng ◽  
Hui Wang ◽  
Shujian Xie ◽  
...  
Keyword(s):  
Water Injection ◽  
Sedimentary Facies ◽  
Production Performance ◽  
Water Flooding ◽  
Tight Oil ◽  
Oil Reservoir ◽  
Reservoir Water ◽  
Injection Efficiency ◽  
Tight Oil Reservoir ◽  
Channel Bar

It is important to determine the reasonable injection and production rates in the development of multilayer tight oil reservoir with water flooding treatment. Based on the INSIM (interconnection-based numeric simulation model), a connected network model, a new method is designed to evaluate the water injection efficiency of different layers in water flooding reservoirs and to optimize the injection-production system to produce more oil. Based on the types of sedimentary facies and corresponding injection-production data, the interwell connections are divided into four major categories (middle channel, channel edge, middle channel bar, and channel bar edge) and twelve subclasses. This classification standard of interwell connections could help to significantly improve the accuracy of judging the dominant flow path without constructing a complicated geological model. The interaction of interwells such as injection-production correlation and water injection efficiency could be revealed by simulating the production performance and computing the layer dividing coefficient and well dividing coefficient. A numerical example is used to validate this method by comparing results from FrontSim and this method, and the computational efficiency of this method is several dozen times faster than that of the traditional numerical simulation. This method is applied to quickly optimize the production schedule of a tight oil reservoir with the water flooding treatment, that is, the water injection rate of multilayer reservoirs could be optimized subtly by the injection efficiency of different layers, and the target of producing more oil with lower water cut could be achieved.

Numerical modeling of seismic responses from fractured reservoirs in 4D monitoring. Part one: seismic responses from fractured reservoirs in carbonate and shale formations

Geophysics ◽  
2021 ◽  
pp. 1-93
Author(s):  
Vladimir Leviant ◽  
Naum Marmalevsky ◽  
Igor Kvasov ◽  
Polina Stognii ◽  
Igor Petrov
Keyword(s):  
Numerical Modeling ◽  
Oil And Gas ◽  
Fractured Reservoirs ◽  
Main Tool ◽  
Time Lapse ◽  
Single Fracture ◽  
Fractured Reservoir ◽  
Seismic Responses ◽  
Shale Formations ◽  
Fracture Opening

One of the most urgent problems of oil and gas reservoir monitoring is the assessment of fractured reservoir infill type – with fluid-filled, gas-filled or closed (no-reservoir situation) fractures, which is of significant value for time-lapse seismic technology. We used the grid-characteristic method (GCM) for numerical modeling of seismic responses from fractured periodic elasto-acoustic structures. We consider every single fracture individually (without using the effective medium approach), and set explicit boundary conditions on fracture surfaces. We assume realistic height-to-thickness ratios – fracture opening (aperture) – equaling 3 to 5 orders of magnitude. These techniques make our models as close to real fractured reservoirs as possible. Analyzing the simulated seismic responses, we solve the problem of assessing fractured reservoir infill type. As a result, previously unknown properties of seismic responses from fractured reservoirs were revealed. We use AVO as the main tool for the analysis of fracture infill type effect on the seismic response in three frequency ranges. Three out of four models exhibit a stable positive AVO gradient regardless of the rock type and frequency range. The analysis of linearized Zoeppritz equations confirms such AVO behavior. We proposed quantitative criteria (indicators) for recognition of a fracture infill type. Amplitude-frequency analysis is shown to expand the capabilities of infill type recognition. Thus, a method for determining fractured reservoir infill type is established for carbonate and shale formations, which could become the basis for a new direction in time-lapse technology.

Numerical Simulation Study on Advanced Water Injection for Fuyang Ultra-Low Permeability Fractured Reservoir

2013 ◽  
Vol 421 ◽  
pp. 286-289
Author(s):  
Hui Hui Kou ◽  
Xian Gui Liu ◽  
Han Min Xiao ◽  
Ling Hui Sun ◽  
Dong Dong Hou ◽  
...  
Keyword(s):  
History Matching ◽  
Large Scale ◽  
Water Injection ◽  
Sedimentary Facies ◽  
Oil Field ◽  
Water Flooding ◽  
Small Scale ◽  
Low Permeability ◽  
Fractured Reservoir ◽  
Production Ratio

According to the features of low porosity and low permeability fracture as well as small scale of channel development, frequent sedimentary facies changes of planar sandstone, poor connectivity, large variation of sequence thickness and great development difficulties for oil layer in Fuyang Oilfield. In this paper, on the basis of fully considered of fracture features, built a more accurate 3-D geological model. And on the basis of the history matching, determined the formation pressure maintenance level under different injection-production ratio and rational water-flooding timing by the simulation of the different programs in the process advanced water injection development. The results show that: the reasonable injection-production ratio of Fuyang oil layer is 1.4, and the rational water-flooding timing is three months after advanced water injection. This provides theoretical guidance for the large-scale development of Fuyang oil layer, and also provides the technical basis for the developing of the other low permeability fractured oil field by advanced water injection.

A New Methodology of Production Performance Prediction for Strong Edge-Water Reservoir

2020 ◽  
Vol 143 (8) ◽  
Author(s):  
Angang Zhang ◽  
Zifei Fan ◽  
Lun Zhao ◽  
Jincai Wang ◽  
Heng Song
Keyword(s):  
Performance Prediction ◽  
Water Saturation ◽  
Water Injection ◽  
Material Balance ◽  
Water Reservoir ◽  
Production Performance ◽  
Water Flooding ◽  
Gas Oil ◽  
Permeability Model ◽  
Water Influx

Abstract Material balance is a basic principle in reservoir engineering, which is still used as a quick and easy analytical tool for reservoir evaluation. In this article, a new methodology of production performance prediction for water-flooding reservoir was proposed based on the material balance principle, which considers the water saturation change caused by water injection and natural water influx, and its effect on transient gas–oil ratio. Among them, the cumulative water production was calculated based on Tong’s water-driver performance curve; the cumulative water influx was obtained by the Fetkovitch method; the transient gas–oil ratio can be acquired by Darcy’s law and Baker’s relative permeability model. Comparisons have been made between the new methodology and commercial reservoir simulator for two different reservoirs. The results show that there is good similarity between these two tools, which verifies the correctness of the new methodology.

FRACTAL ANALYSIS OF FRACTURE INCREASING SPONTANEOUS IMBIBITION IN POROUS MEDIA WITH GAS-SATURATED

2013 ◽  
Vol 24 (08) ◽  
pp. 1350056 ◽  
Author(s):  
JIANCHAO CAI ◽  
SHUYU SUN
Keyword(s):  
Fractal Analysis ◽  
Fractured Reservoirs ◽  
Spontaneous Imbibition ◽  
Gravity Force ◽  
Single Fracture ◽  
Liquid Density ◽  
Fractured Reservoir ◽  
Single Plane ◽  
Matrix Blocks ◽  
Wetting Liquid

Spontaneous imbibition (SI) of wetting liquid into matrix blocks due to capillary pressure is regarded as an important recovery mechanism in low permeability fractured reservoir. In this paper, an analytical model is proposed for characterizing SI horizontally from a single plane fracture into gas-saturated matrix blocks. The presented model is based on the fractal character of pores in porous matrix, with gravity force included in the entire imbibition process. The accumulated mass of wetting liquid imbibed into matrix blocks is related to a number of factors such as contact area, pore fractal dimension, tortuosity, maximum pore size, porosity, liquid density and viscosity, surface tension, contact angle, as well as height and tilt angle of the fracture. The mechanism of fracture-enhanced SI is analyzed accordingly. Because of the effect of fracture, the gravity force is positive to imbibition process. Additionally, the farther away from the fracture top of the pore, the more influential the hydrostatic pressure is upon the imbibition action. The presented fractal analysis of horizontal spontaneous imbibition from a single fracture could also shed light on the scaling study of the mass transfer function between matrix and fracture system of fractured reservoirs.

Fractured Reservoir Blocking Dosage Calculation Method

2012 ◽  
Vol 268-270 ◽  
pp. 772-775
Author(s):  
Shuo Liang Wang ◽  
Yang Ming Liao ◽  
Huang Chang Xie
Keyword(s):  
Program Design ◽  
Water Injection ◽  
Blocking Agent ◽  
Water Flooding ◽  
Fluid Loss ◽  
Fractured Reservoir ◽  
Sweep Efficiency ◽  
Reservoir Properties ◽  
Dosage Calculation ◽  
Profile Control

Fractured reservoir development process are often faced with the angle wells flooded serious and side wells don’t get the effect of water injection. In order to increase the water flooding sweep efficiency. Profile control plugging is a measure that is frequently used. Traditional plugging program design does not take into account the fluid loss, Program design of the blocking agent dosage is always small, the result is not satisfactory. In this paper, the classic percolation theory is used, seepage equation of the fracture system and matrix system is established, the blocking agent Filtrate analytical solution that considers the different reservoir properties and different blocking agent performance is obtained, that can be used to guide the design of profile control water plugging program and can calculate the best blocking agent dosage. Through the actual implementation of the effect, the proposed method can be more substantial increase in the effect of plugging.

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