Complex Fault Block Reservoir Research Articles

Experimental Study on Improving Oil Recovery Mechanism of Injection–Production Coupling in Complex Fault-Block Reservoirs

In order to improve the effect of injection–production coupling development to improve crude oil recovery in complex fault-block reservoirs, we carried out a physical simulation experiment based on a sandpack model of transforming water-driven development into injection–production coupling development and quantitatively evaluated the influence of rounds of injection pressure coupling on the crude oil mobilization in reservoirs with different permeability levels and on oil recovery. Meanwhile, the characteristics of residual oil were studied via a numerical simulation method. The mechanism of increased oil production via injection–production coupling development was revealed by analyzing the water and oil contents, formation pressure, and streamline fields through the establishment of mechanism models. The results of the physical experiment show that injection–production coupling can improve the recovery effect of medium- and low-permeability reservoirs by 55.66%. With an increase in the injection pressure, the oil recovery percentage of the low-permeability sandpack model at 20 MPa is 100%, and this study finds that injection–production coupling is the main way to develop the recoverable oil in a low-permeability reservoir. The numerical simulation results show that among the four remaining oil distribution types (interwell-enriched, low-permeability zone-enriched, well network imperfection, and mismatch between injection and production), the interwell-enriched type of the remaining oil reserves accounts for the highest proportion (48.52%). The simulation results of the mechanism model show that water-driven development easily leads to streamline solidification, resulting in ineffective circulation of the injected water. Compared with conventional water-driven development, the pressure propagation range is significantly increased in injection–production coupling development. The reservoir streamline distribution is more continuous and uniform, and the flooding wave is wider in volume and range. This research provides a theoretical basis for the injection–production coupling technology policy in complex fault-block reservoirs.

Numerical Simulation Study on Optimization of Injection-Production Coupling Parameters in Complex Fault Block Reservoirs

Taking complex fault-block reservoir in Biyang Depression as the research object, the influence of different factors on the coupling development mode of injection-production was studied. The numerical simulation method was used to evaluate the influence of intervention timing, injection intensity, periodic injection volume and production strength on the coupling implementation effect of the fault-block reservoir, and the coupling development parameters were optimized.The main knowledge obtained is that the timing and intensity of intervention are the main controlling factors of injection-production coupling in fault block reservoirs. The earlier the intervention time, that is, the lower the water cut, the better the injection and production coupling development effect. There is an optimal injection intensity, and the coupling injection and production effect is the best when the injection and production ratio is kept at 1:1. When the pressure is restored to 100%-120%, the coupling injection and production development effect is the best, and the periodic water injection volume is 2400-3200m3. The higher the strength of liquid production, the faster the oil recovery rate.

Numerical Simulation of Oil Displacement in Complex Fault Block Reservoir

Numerical Simulation of Oil Displacement in Complex Fault Block Reservoir

Establishment of sample pool and prediction of saturation field in complex fault block reservoir based on deep learning algorithm

The remaining oil prediction of complex fault block reservoir is the key to guide the well deployment in the late high water cut stage. We formed the construction methods of 20,000 numerical simulation forward models, including the dynamic and static attributes of the reservoir, such as structural depth, reservoir thickness, permeability, porosity, injection and production fluid volume, etc. The saturation field distribution of each model is obtained through numerical simulation, so as to form the saturation field characteristic data sample database. Through the deep convolutional generative adversative neural network model, the data of sample pool was trained, in which 70% of the data was randomly selected as the training set and 30% of the data as the test set. Finally, the saturation field prediction method that could be applied to an actual block was established. The result showed that: the new method did not need to carry out the numerical simulation research on the actual region, the remaining oil saturation distribution at different time step that obtained by the deep convolutional generative adversative neural network model only need to input the reservoir physical parameters, well location coordinates, injection production and other information of the actual block, and the prediction accuracy of the method was more than 90%. The test showed that the deep convolutional generative adversative neural network model had good generalization ability, and the model could be widely used in the prediction of residual oil saturation field of complex fault block reservoirs, which greatly improved the efficiency of reservoir research.

Study on water flooding law in high water cut stage of complex fault block reservoir

In recent years, with the progress of science and technology and the development of times, it has brought great opportunities for the development and protection of Tibetan resources in our country. Many reservoirs are located in very complex fault blocks with small fault blocks and many faults, coupled with strong heterogeneous media. After years of waterflooding development, they have entered the high water cut oil recovery stage. In view of this, this paper will focus on the analysis of the water drive law in the high water cut stage of complex fault block reservoirs, and carry out specific strategy optimization for increasing production, in order to promote the exploration of the law of high water cut area in complex fault block reservoirs.

Analysis of Channeling-Path Phenomena in a Complex Fault-Block Reservoir with Low Recovery Factor and High Water-Cut Ratio

Current methods for the analysis of channeling-path phenomena in reservoirs cannot account for the influence of time and space on the actual seepage behavior. In the present study, this problem is addressed considering actual production data and dynamic characteristic parameters quantitatively determined in the near wellbore area by fitting the water-cut curve of the well. Starting from the dynamic relationship between injection and production data, the average permeability is determined and used to obtain a real-time quantitative characterization of the seepage behavior of the channeling-path in the far wellbore area. For the considered case study (Jidong oilfield), it is found that the seepage capacity of the channeling-path in the far wellbore area is far less (10 times smaller) than that of the channeling-path in the near wellbore area. The present study and the proposed model (combining near wellbore area and far wellbore area real-time data) have been implemented to support the definition of relevant adjustment measures to ultimately improve oil recovery.

Reservoir Quality and Its Control Factors of Complex Fault Block Reservoir in Continental Faulted Basin, Case Study in the Wang Guantun Area, Bohai Bay Basin, China

Continental faulted basins are widely distributed in eastern China. Many of these basins, in which the faults block oil and gas reservoirs, have been explored. The heterogeneity of the reservoirs in fault block is very strong, shich restricts the further efficient development of these kinds of oil and gas fields. In this study, porosity and permeability tests, the use of thin sections of rock, mercury injection experiment and CT scan were used to investigate reservoir quality characteristics and control factors. The results showed that the content of quartz, feldspar, and debris in rock had a significant control function on the quality of the reservoir. Reservoir performance improved with increase of quartz and feldspar content, and worsened with increase of debris content. Taking the Ek1 reservoir in the Wang Guantun area as the specific research object, we developed the following understanding. On the one hand, the main compaction in the study area was mechanical compaction. When the compaction rate was greater than 60%, the porosity and permeability were inversely proportional to the compaction rate. On the other hand, dissolution pores were relatively developed in the study area, and the main types of dissolution were intragranular and intergranular dissolution pores. When the surface porosity of the dissolution pore was over 9.2%, porosity increased significantly the increase of dissolution surface porosity. This showed that dissolution surface porosity had greatly improved the reservoir porosity in this range.

Integrated Geologic Modeling of Fault-Block Reservoir: A Case Study of Ss Oil Field

The Ss oil field is found in the Turpan-Hami Basin’s Taipei Sag’s arc structural belt. This reservoir has a complicated character that has a significant impact on reservoir modeling and production prediction. This is a fault-block reservoir with ultralow permeability and low porosity that is divided by 57 faults. A static model was constructed by Petrel software based on reinterpretation of original log and core data and seismic information so as to clarify the spatial distribution of oil and water in the reservoir and to fit the development history of the later simulated reservoir. The integrated geological modeling approach is described in this work using the Ss reservoir as an example. A 3D structural model was built based on the spatial cutting relationship between the layer model and the fault, and the model’s quality was improved by breakpoint data, which more correctly depicted the structural properties of the research area. The lithofacies model was built within the restrictions of sedimentary facies using the sequential Gaussian simulation (SGS) stochastic modeling approach, which is paired with variogram data analysis to achieve the range value. To obtain the porosity and permeability model, the empirical formula of porosity and permeability, the SGS method, and the variation range value was input into the lithofacies model. It is important to note that the input lithofacies and property models have values of the same range. To gain the water saturation model, the distinct S w function formulas of the S 1 ~ S 4 layer derived from the J S w function were fed into the software. The NTG model was created according to the lower limit of porosity, which is 11%. The merging of detailed reservoir description and simulation led to the establishment of the Ss reservoir geological model. In the plane, the scale of the geological model has reached the meter level and decimeter level in the longitudinal direction. It also offers a framework for optimum reservoir modeling for complex fault-block reservoirs. This method improves the accuracy and precision of the model by reflecting the reservoir’s heterogeneity and the oil-water distribution. It could provide more details for future reservoir research such as fine reservoir simulation.

Fine Geological Modeling of Complex Fault Block Reservoir Based on Deep Learning

Nowadays, people’s demand for underground mineral resources is increasing, and geological disasters have occurred frequently in recent years. Geological disasters refer to geological effects or geological phenomena that are formed under the action of natural or man-made factors, causing loss of human life and property, and damage to the environment; such as landslides, collapses, mudslides, and ground subsidence. Under such a background, people must accelerate the exploration of complex geological structures. This paper is aimed at using the methods and concepts of deep reinforcement learning. Deep learning is to learn the inherent laws and representation levels of sample data. The information obtained during these learning processes is of great help to the interpretation of data such as text and images. In this way, the fine geology of complex fault-block reservoirs is modeled and studied. Geological structures and phenomena are discussed through convolutional neural network models and computer techniques. At the same time, the multitask bird recognition network is used to extract and classify geological images, so as to construct geological model maps with different spatial structures. Finally, the quality of the fault reconstruction model, the calculation of reservoir geological simulation reserves, and the evaluation of the water injection development effect of complex fault blocks are analyzed. In the evaluation of the development effect of water injection in complex fault blocks, comparing the relationship curve between the actual comprehensive water content and the oil recovery factor with the standard curve, the comprehensive water content of the initial block increased rapidly. Through timely and dynamic water allocation and comprehensive management, the water cut rising speed is controlled. The current comprehensive water cut of the reservoir is between 60% and 80%, the actual curve is between 25% and 35%, and the estimated waterflooding recovery is about 30%.

Study of Well Pattern Optimization Techniques in High Dip Angle Fault Block Reservoir

The study area is a narrow complex fault block reservoir, which is characterized by large strata dip, large reservoir thickness and strong interlayer heterogeneity. At the initial stage of development, a set of stratigraphic series is adopted for development. At present, there are problems of unbalanced utilization between layers and rapid rise of water cut. In order to meet the needs of overseas oilfields to improve the oil production rate during the development period, this paper analyses the geological and development affecting factors of high productivity wells through the study of fine reservoir geological body, the quantitative characterization and distribution of remaining oil. Moreover, the optimization of the development pattern of small well spacing is studied. Through changing the development mode, adjusting the well pattern layer series, and deploying a set of well pattern in the fault area and enrichment area with remaining oil inter well in three dimensions to develop the oil layers with poor production of old wells, stereoscopic potential tapping can be attained. The method of layer by layer upward development is adopted, and the production is carried out in batches vertically, so as to reduce the contradiction between layers and increase the degree of reserve production, improve the oil production rate and recovery degree during the development period of the oilfield finally.

Laboratory experimental study on the binary combination flooding system in low permeability conglomerate reservoir

In view of the poor injection-production effect of low permeability conglomerate complex fault block reservoir in Xinjiang Oilfield in the late development stage of high water cut, the indoor experimental study of binary compound flooding system was carried out. By compounding the petroleum sulfonate and polymer binary system, the viscosity and morphology parameters of the binary compound flooding system were measured. The microscopic pore structure of the core in this block was analyzed by GE Phoenix Nanotom S, and four groups of experimental schemes were designed to study the oil displacement efficiency of the whole diameter core binary compound flooding system. The experimental results showed that the binary system of surfactant and polymer showed additive synergistic effect. The performance of binary compound system is less affected by polymer molecular weight and solution concentration, which meets the viscosity requirement of low permeability conglomerate for binary compound flooding system. The porosity of samples is relatively small and the connectivity between pores is relatively poor. The experimental results of physical model oil displacement efficiency show that the oil recovery can be increased by more than 17% by injecting 0.3PV 1200mg/L polymer + 0.5% (w) surfactant binary compound system.

Feasibility Study for Well pattern Encryption in Complex Fractured Block Reservoirs--Taking the Liu 90 South Fault Block in the Jidong Oilfield as an example

Jidong oilfield belongs to complex fault block reservoir, and the development has now entered into high water-cut stage. when using Well pattern encryption technology to stabilize production, it is necessary to study the feasibility of Well pattern encryption to ensure a better economic benefit. In this paper, we use theoretical analysis method, consider the influence of oil price on the calculation, improve the economic limit Well pattern density calculation formula, calculate the economic limit Well pattern density under different recovery rates, make recovery rate prediction for different Well pattern density scenarios by combining with Sherkachov's formula, and use the curve intersection method to determine the Well pattern density at the break-even point, so as to determine the economic feasibility of Well pattern encryption. The example calculations show that the use of well network encryption alone does not meet the development requirements of the Liu 90 South block and has no significant economic benefits, so a combination of two-three methods is needed to further improve the recovery rate. Numerical simulation prediction results show that the two-three combination method can improve the recovery rate by 14.54%, accumulate 28.88×104t of oil increase and increase revenue by 678,245,000 yuan.

Study on air foam flooding technology to enhance oil recovery of complex fault block reservoir by water injection

In order to solve the problem of rapid increase in water content and decrease in production after water flooding in fault block reservoirs, the air foam flooding experiments of static low temperature oxidation, single and double sand filled tube were carried out. The results showed that there was no absolute relationship between oxygen consumption and viscosity of crude oil, and there was a turning point of water saturation. The reaction rate is greatly affected by the reaction temperature. The displacement efficiency of single pipe is increased about 15%. The injection of air foam can effectively block the high permeable strip, and the middle low permeability layer is effectively utilized, and the recovery ratio is increased by about 10.9%. The plan of air foam flooding for Gao 16 block is compiled. The injection volume is 0.1PV and the gas-liquid ratio is 2:1. The recovery factor is increased by 5% and the cumulative oil increment is 22700 tons.

Description and Understanding of Complex Fault Block Reservoir Geology

Reservoir description is an important step in oilfield development. Before mining, using various technical means to analyze and study oilfield structure can achieve the purpose of fully understanding the reservoir and provide theoretical basis for reservoir development. In this exploration, the background of description of complex fault block reservoir geology is analyzed, and X35 reservoir is selected as the research object to study the regional geological reservoir. By analyzing the fault distribution characteristics of X35 reservoir, the reservoir strata are divided. The three-dimensional (3D) geological model of the reservoir is established by using the method of facies-controlled modeling and numerical simulation. Finally, the 3D geological model is tested. The results show that the model has high accuracy and reflects the distribution of X35 reservoir, which has a certain guiding significance for the exploration and effective development of the remaining oil in the reservoirs distributed in this area.

Prediction method of formation pressure for the adjustment well in the reservoir with fault

Adjustment wells need to be deployed in the middle and late stages of oilfield development to improve development efficiency. However, the multiple pressure systems would be happened in the fault block oilfields due to the geological faults are developed and multi-layer joint water injection. The well kick and leakage would happen during drilling and completion operations of adjustment well because of the large dynamic pressure changes such as high-pressure or low-pressure. A pressure prediction method established base on seepage theory and fluid mechanics theory in order to ensure the safety operations during the adjustment well drilling and completion. This method could predict the maximum formation pressure of adjustment wells in complex fault block reservoirs by considering the influence of faults and surrounding injection-production wells. The error between prediction results and numerical simulation results is less than 10% based on Bohai fault block oilfield. The scheme of shut-in of surrounding water injection wells during drilling and completion of adjustment wells in fault block oilfield is given. This method has significance guidance for the design of shut in adjustment well drilling and completion.

Effects of the interaction of tectonics, eustasy, climate, and minerals on the sedimentary evolution of early-middle Jurassic in the Hongshanzui region in Junggar Basin

Majority of the oilfields in the Hongshanzui region are small and complex fault block reservoirs, and the evolution of the sedimentary system under the sequence stratigrapic background has been a controversial topic. Six middle-term base-level cycles were divided, and eight types of lithofacies assemblages were recognized based on the stacking patterns and volumetric partitioning according to the core, well logs, and seismic data correlated with the field investigation of outcrops. Furthermore, the evolution of the sedimentary system under the sequence stratigraphic framework was clarified. Among the six middle-term base-levels, MSC1 belongs to the retrogradational system tract, and the sediment distribution exhibits the characteristics of “large plain and small front.” MSC2 belongs to the transgression system tract, and the sediment distribution exhibits has the characteristics of “small plain and large front.” In the case of MSC5 and MSC6, the sediment distribution exhibits the characteristics of “dominant channel and repeated channel-switching.” Further, the controlling factors of tectonic, base level, climate, and minerals are discussed.This research has been applied to the exploration and development of the Hongshanzui oilfield, and a certain benefit has been achieved.

Research and Application of Fine Intelligent Injection Technology of Cable Type in Dagang Oilfield

Dagang oilfield belongs to typical multi-layer system, heterogeneity of complex fault block reservoir, reservoir and the large difference of physical property of crude oil, water, etc, the longitudinal permeability difference is obvious, separate injection interval is not detailed, The existing bridge eccentric note, bridge concentric injection technology can’t meet the needs of the fine water injection, real-time measurement and control because of drift, well depth, pressure and other factors, and there is poor adaptability, measuring problem of long time and low efficiency. Cable type fine intelligent water injection technology in underground intelligent water distributor, the ground controller as the core tools, cable as transmission medium, the computer network communication technology, intelligent control technology combined with oil field water injection demand, developed a new and reliable water injection system, realized the layered injection allocation under different deviation, full automatic control and monitoring data, and direct reading test. The technology in the implementation of 5 Wells in dagang oilfield, the implementation of maximum deviation 80 °, the maximum depth of 3661.52 m, the highest water flooding pressure 25 mpa, construction success rate reaches 100%, downhole test times 5 Wells, inspection accuracy of 100%. The results show that the cable type intelligent water flooding technology can not only realize downhole data real-time monitoring, real-time traffic regulation, and can complete the packer direct reading test, and the measurement process is reliable and efficient, at the same time solve the high Angle well, horizontal well can’t test the technical problem, provides the high Angle well, horizontal well fine water injection technology support.

Production optimization for alternated separate-layer water injection in complex fault reservoirs

Complex reservoirs possess some principal characteristics, such as strong geological heterogeneity, faults and multi-layers, etc. They can exert significant effects on the flow performance of water flooding vertically and horizontally. For most large-scale and well-connected reservoirs, water injection wells generally adopt manual adjustment method or intelligent well technology to control the water injection volume of a single well. However, these technologies are associated with high costs, and it is not a trivial task to obtain an optimal injection-production control for some complex reservoirs with small blocks or strong heterogeneity. More importantly, most complex fault block reservoirs have experienced multiple rounds of well pattern infilling adjustment in the development process, with large well pattern density, as well as because of complex structure, fault development and single injection production form of fault block reservoir. In view of the unbalanced vertical production of fault block reservoirs in high water cut stage, the alternative injection production mode is proposed to minimize the interlayer interference and achieve stable production under unstable injection production. However, the key parameters of the alternative injection production method are not clear and need to be optimized. Facing this situation, a new method for the injection-production optimization is proposed in this paper. This technology use underground regulator which can alternately open and close the different layers. Additionally, the heterogeneity of permeability is considered and a uniform displacement of water in each flooding unit is realized by adjusting the regulators of injectors and producers. By using this method, a series of measurements such as on-off time and injection volume can be chosen as decision variables. Hence, the commercial simulator and the optimization theory algorithm are used to optimize and adjust the alternative stratified water injection technology. Additionally, this method can be combined with field practice, save the cost of measurement and adjustment, and be easy to operate. This method can be combined with field practice, save the cost of measurement and adjustment, and be easy to operate. Detailed parameter optimization and results are presented with an example to prove the efficacy of the proposed methodology. The results show that the method proposed in this study can be successfully applied to optimization of well control and improve the reservoir development significantly.

Asynchronous Injection-Production Process: A Method to Improve Water Flooding Recovery in Complex Fault Block Reservoirs

The complex fault block reservoir has the characteristics of small area and many layers in vertical. Due to the influence of formation heterogeneity and well pattern, the situation that “water fingering is serious with water injection, on the contrary, driving energy is low” frequently occurs in water flooding, which makes it difficult to enhance oil recovery. Asynchronous injection-production (AIP) process divides the conventional continuous injection-production process into two independent processes: injection stage and production stage. In order to study oil recovery in the fault block reservoir by AIP technology, a triangle closed block reservoir is divided into 7 subareas. The result of numerical simulation indicates that all subareas have the characteristic of fluid diverting and remaining oil in the central area is also affected by injected water at injection stage of AIP technology. Remaining oil in the central area is driven to the included angle and border area by injected water and then produced at the production stage. Finally, the oil recovery in the central area rises by 5.2% and in the noncentral area is also increased in different levels. The AIP process can realize the alternative change of reservoir pressure, change the distribution of flow field, and enlarge the swept area by injected water. To sum it up, the AIP process is an effective method to improve the oil recovery in complex fault-block reservoir by water flooding.

Reservoir characteristics and three-dimensional architectural structure of a complex fault-block reservoir, beach area, China

The objective area in this paper is a complex fault-block reservoir, which is provided by China Petroleum Engineering Design Competition. Reservoir characteristics which comprise of stratigraphic features, vertical changes, and section properties (thickness, percentage sand, and percentage amalgamation) are documented. Through comprehensive analysis on structural architecture and reservoir characteristics, a three-dimensional quantitative reservoir modeling is taken at a regional scale of 69 × 97 × 37 m3 with the application of geostatistics as theoretical guidance. Then, a high-resolution hierarchical reservoir model of this field has been generated with a combination of hierarchical, structural, physical, and well trajectory data. The established three-dimensional geological model integrates all well and structural information, which can provide a basic model for subsequent sedimentary microfacies modeling and property modeling as well. Finally, a series of profiles are built successively, they are three-dimensional fence diagrams, connecting well sections and well group profiles, which can be a valuable tool for reflecting geologic body with great reality and thus achieve reservoir characterization of the complex fault-block reservoir.