Low Production Wells Research Articles

Technology and Research on Improving Oil Recovery by Volume Fracturing with Phase Change Permeability in Ultra-low Permeability Reservoirs

Abstract The conventional water injection development production wells in ultra-low permeability reservoirs have low efficiency, low production and low liquid content, and poor economic benefits. Traditional water drive development techniques are difficult to adapt to the requirements of economically effective development in ultra-low permeability reservoirs. Therefore, it is urgent to adjust development ideas and transform water injection development methods. A major development experiment was carried out in the Y284 area of Huaqing Oilfield to transform the water injection development method. Based on the mechanism of reverse osmosis flooding in oil recovery wells, this article uses dynamic monitoring technologies such as downhole microseismic to achieve three-dimensional reservoir transformation, and establishes a large-scale fracturing technology of “collaborative permeability flooding, volume fracturing, and multi-stage temporary plugging” for reverse osmosis wells in ultra-low permeability reservoirs. Research has shown that large-scale fracturing technology for water injection wells can improve single well oil recovery speed by increasing the complexity of fracture networks. The important factors affecting the effectiveness of water injection wells include reservoir properties, fracturing transformation scale, cumulative water injection volume, remaining oil distribution, and heterogeneity of aquifers. At the same time, the construction parameters of large-scale volume fracturing for water injection wells, namely 140-170m, are quantitatively determined based on the actual situation of the mining field ³ The amount of sand added, a sand ratio of 17-22%, and a large displacement of 8-10m3/min, 1400-2000m ³ The amount of liquid entering the ground can most effectively achieve the conditions for reservoir transformation. The conclusion is that large-scale fracturing technology for conversion wells provides technical support for volume fracturing and optimization design of fracturing parameters for low production wells in ultra-low permeability reservoirs, and can provide guidance and reference for the efficient development of other similar ultra-low permeability reservoirs.

Research and Application for Alternate Production Technology of Dual-Branch Horizontal Wells in an Offshore Oilfield

Old-well sidetracking is a key method for controlling low-productivity wells in the Bohai oilfield. This study employs reservoir engineering and numerical simulation techniques to investigate the maximum drainage radius and natural coning control mechanism in heavy-oil reservoirs with bottom water. Based on these findings, an alternate production technology was developed for dual-branch horizontal wells. The technology creates a new branch through sidetracking, connecting and isolating the old and new wellbores using a combination of wall hangers and branch guides. Initially, the old wellbore with an ultra-high water cut is temporarily sealed. When the new branch reaches a high water-cut stage, production is switched back to the old wellbore. This technology was successfully applied to three wells in the Bohai oilfield, resulting in the new branch achieving expected production levels, while reopening the old wellbore increased daily oil output by 27 m3 and reduced water cut by 5.6%. Cumulative oil production from these wells reached 95,000 m3. This technology improves well-slot resource utilization, enhances recovery rates, and has significant potential for broader application.

Research and Application of Treatment Measures for Low-Yield and Low-Efficiency Coalbed Methane Wells in Qinshui Basin

China is rich in high-grade coalbed methane resources, accounting for one-third of the total amount of coalbed methane resources. Qinshui Basin is the main high ranking coalbed methane mining basin in China. In the early stage of CBM development, low-production and low-efficiency wells were formed in the process of block development because of an insufficient understanding of reservoir geological conditions. The existence of low-yield and low-efficiency wells with low output and a poor development benefit seriously restricts the efficient development of coalbed methane. In order to improve the overall development efficiency of coalbed methane fields, how to revitalize low-yield and low-efficiency wells is the main problem facing the development process of coalbed methane. With the deepening understanding of the study area geology, the formation of low-yield and low-efficiency wells has been basically identified. With the advancement of development technology, developers have the ability to retrofit some low-producing and inefficient wells. Low-production and low-efficiency wells are widely distributed. It is difficult to find the criteria for classifying low-producing and low-efficiency wells because of the great differences in geological conditions and reservoir physical properties in different blocks. In addition, the causes of a low-production and low-efficiency well are complex, as the same well is often caused by many reasons, and how to identify the causes of low-production and low-efficiency wells is difficult. In recent decades, developers have studied many methods to retrofit low-production wells, but the retrofit results are not satisfactory. How to choose an economical and efficient reservoir reconstruction method to revitalize low-production and low-efficiency wells is particularly important. This paper starts with the definition of low-production and low-efficiency wells in different blocks, combining an economic evaluation and productivity characteristics to judge whether they are low-production and low-efficiency wells, and defines the distribution of low-production and low-efficiency wells in blocks. The reasons for the formation of low-production and low-efficiency wells are analyzed with the geological characteristics, production dynamic performance, and engineering reconstruction effects. This paper makes a comparative analysis of the current relatively mature low-production and low-efficiency well treatment measures, clearly identifies the advantages and disadvantages of different treatment measures, and takes corresponding stimulation measures for different causes of low-production and low-efficiency wells. The research shows that there are 687 low-production and low-efficiency wells in block A, accounting for 69.4% of the total number of wells, and the low-production and low-efficiency wells account for a relatively large proportion; so, it is necessary to treat them. The main causes of low-production and low-efficiency wells are geology, engineering and drainage systems. The geological reason mainly refers to the low gas production of coalbed methane wells influenced by three factors: resource abundance, faults, and collapse columns. According to the different causes, three treatment measures of large-scale secondary fracturing, temporary plugging, and diversion fracturing and foam fracturing are put forward. The research method in this paper is targeted at different geological conditions so it can be used to guide the treatment of low-yield and low-efficiency wells in other CBM blocks, and it has very important significance for revitalizing the existing low-efficiency CBM assets and improving the development efficiency of CBM.

Construction and application of workover priority evaluation model for surface coalbed methane low production wells based on Entropy-TOPSIS

Affected by geology and mining, a certain number of low-yield wells will appear after a period of production in coalbed methane wells, and technical repairs are urgently needed to restore their production capacity to the maximum. Therefore, it is of great significance to establish a reasonable and feasible theoretical standard to evaluate the workover priority of CBM wells for the efficient utilization of CBM resources. From the perspectives of technical feasibility and economic rationality, eight key indicators that affect the cost performance of CBM well workover are screened. Combining the entropy value method and the TOPSIS comprehensive ranking method, the surface coalbed methane well repair priority entropy value-TOPSIS comprehensive evaluation model was constructed, and the surface coalbed methane well repair priority evaluation was carried out by taking 9 surface coalbed methane wells that urgently needed to be repaired in a mine as the evaluation objects. The evaluation results show that among the economic indicators, the average gas production per meter in the 30 days before the coal bed methane well was stopped and the cumulative gas production per meter before the stop had a relatively high weight, which were 29.68% and 13.83% respectively, This shows that in coalbed methane well workover operations, the long-term gas production potential of the coalbed methane well and the gas production capacity when disturbed by harmful factors are the decisive factors affecting the priority of coalbed methane well workover; Among the technical indicators, the degree of casing deformation and the depth of the coalbed methane well have a relatively high weight, accounting for 11.34% and 9.90% respectively, This shows that the smaller the deformation of the wellbore casing and the shallower the depth of the coalbed methane well, the higher the priority of the workover of the coalbed methane well; The ranking of the production recovery rates of the three coalbed methane wells in the Pingdingshan mining area after workover operations is consistent with the results output by the evaluation model, which proves that the evaluation model is reasonable for determining the priority of workovers for damaged wellbores; This evaluation model can provide a theoretical reference for small and medium-sized coalbed methane development companies to determine the priority of workovers.

大庆长垣扶余油层致密油低产井控制因素分析及增产技术对策

大庆长垣扶余油层致密油低产井控制因素分析及增产技术对策

Cause analysis of low production and low efficiency Wells and treatment countermeasures

Cause analysis of low production and low efficiency Wells and treatment countermeasures

Geological Characteristics of Low-Yield and Low-Efficiency CBM Wells and Practical Measures for Production Increase in the Qinshui Basin.

Many low-production and low-efficiency wells in the Zhengzhuang, Fanzhuang, Lu'an, and Yangquan blocks of the Qinshui Basin seriously hinder the development of coalbed methane in China. Through in-depth research on the geological conditions and development technology of coalbed methane, it was found that the main reasons for the existence of a large number of low-production and low-efficiency wells are the fragmentation of coal structure, poor adaptability of vertical well types, sizable well spacing, and mismatched stimulation measures. On this basis, it is proposed to adopt an L-shaped horizontal well and staged Fracking technology in the block with a complete coal structure but low permeability. For stress-concentration areas, the first fracturing of a vertical well has a single crack and a small coverage area; After a period of drainage and production, the use of repeated fracturing technology can increase the complexity of fractures and increase gas production; For the fractured area of coal structure, the use of roof fracturing technology effectively solves the problem of coal fragmentation. In natural fracture development areas, new fractures are formed using fracture turning technology to achieve the effect of increasing production. The above technologies have achieved good results in the Qinshui Basin engineering experiment. Therefore, in-depth research on the geological conditions of coalbed methane and matching related development technologies are the main ways to solve low-efficiency and low-production wells in coalbed methane development blocks.

Research on Fracturing Technology for Low Production and Low Efficiency Casing Damaged Wells

With the further development of Daqing Oilfield, the proportion of casing damaged wells is increasing day by day, because the casing damage location is mostly located in the upper part of the reservoir, the conventional technology can not carry out targeted fracturing construction,the low-yield and low-efficiency wells which limits the efficient development of the oil field. In order to satisfy the needs of subdivision and large-scale fracturing construction of low-yield and low-efficiency wells with casing damage, this paper studied the fracturing design principles, determined the optimal design theory of different types of wells, and can make effective fracturing schemes for different reservoirs and well conditions. At the same time, a kind of small diameter segmented fracturing tools have been developed, which can meet the fracturing operation of wells with diameter above 104mm, so that the number of fracturing segments and the scale of reconstruction are greatly higher than those of conventional technology. 30 wells have been tested in the field, and the effect of increasing oil and injection is obvious. The results show that this process can effectively improve the production status of casing damage, low production and low efficiency wells and increase the productivity of single wells.

Evaluation of Reconstruction Potential for Low-Production Vertical Wells of CBM in the Southern Qinshui Basin

Production practice has shown that not all low-production coalbed methane (CBM) wells can be reconstructed into high-production wells through secondary stimulation, so it is necessary and timely to establish an evaluation index system, form an evaluation method, and evaluate the reconstruction potential of low-production wells. Based on the development practice of CBM in the southern Qinshui Basin, this paper analyzes the influencing factors of low production in vertical wells from the aspects of coal and rock reservoir conditions, drilling and completion engineering, and drainage engineering. It is proposed that the evaluation of the reconstruction potential of low-production wells should focus on the quality of CBM resources, the difficulty of CBM desorption and diffusion, and the degree of damage to coal reservoirs caused by the initial reservoir stimulation. Twelve parameters, including gas content, gas saturation, reservoir pressure gradient, critical desorption–reservoir pressure ratio, and permeability, were systematically selected as evaluation indicators, and the grading reference values for each evaluation indicator were comparatively given. Then, a multi-factor comprehensive evaluation method for the reconstruction potential of low-production wells based on gray correlation analysis method was established. The reconstruction potential of low-production wells was divided into three levels: high, medium, and low. When reconstructing low-production wells, it is recommended to prioritize the low-production wells with high reconstruction potential, followed by those with medium reconstruction potential, while low-production wells with low reconstruction potential are not recommended for reconstruction. Finally, the evaluation method was used to evaluate the reconstruction potential of five low-production wells in a CBM block, and suggestions for the reconstruction order and reconstruction potential levels for each well were given.

Numerical analysis study on the application of three-lobed vortex tube in low-production wells

Numerical analysis study on the application of three-lobed vortex tube in low-production wells

Technology Focus: Artificial Lift (March 2023)

Selecting artificial lift papers for the Tech Focus feature of JPT can be a daunting exercise when technologies and innovations abound, more so post-pandemic, with 157 submitted abstracts covering 2021–2022. In narrowing the offerings to three, the criteria of conformance to guidelines and novelty of information, technical equipment, and application were considered. Industry indicators and interest were also factors. Gas lift remains of high global interest, whether in long horizontal shale oil wells or vertical ones because of the cost to operate lower lifting. Declining production and high gas/oil ratios (GORs) present a challenge for conversion to secondary lift forms. Paper SPE 209721 provides an innovative solution combining gas lift with sucker rod lift to enhance and exploit low-productivity wells in high-GOR fields. Permanent magnet motors (PMMs) have made quite the technical splash in the industry over the past decade. PMMs are one-third shorter and result in higher power densities and power savings of up to 18% just by changing out the induction motor. PMMs are again grabbing attention for the direct 1:1 ratio of electrical to carbon footprint. Current environmental, social, and governance concerns are placing demands on all operators, and PMMs are positioned to help with carbon reduction as a low-hanging fruit in paper SPE 209736. In paper SPE 209763, we look at all-metal progressing cavity pumps (aka M2M), which consist of a metal rotor and metal stator. Incremental advances in geometry and materials continue to see operators use high-temperature fluids with low operational expenditure in mind. Reliability is always a concern, and now a novel condition indicator has been developed and tested that offers a better indicator than pump efficiency alone. Recommended additional reading at OnePetro: www.onepetro.org. SPE 206909 Successful Progressing Cavity Pump Reliability Improvement Project in an Oman Steamflood by Shauna Noonan, Oxy, et al. SPE 211782 Maximizing Marginal Fields Profitability Through Drilling Multilateral Wells To Reduce Well Count and Well Cost: Dual Lateral Well With Single ESP and Smart Lower Completion by Mahmoud Mohamed Abdelhay Mostafa, ADNOC, et al. SPE 209748 Gas Pump—A Gas-Driven Positive Displacement Pump Artificial Lift System by Stephen W. Turk, ELC Energy Services, et al.

Research on Productivity Evaluation Method Based on Shale Gas Well Early Flow Stage Data

Since the accurate early gas well production regime is related to the production period and final productivity, it is crucial to make better use of early flow stage production data for gas well productivity evaluation. Absolute open flow potential (AOF) and estimated ultimate recovery (EUR) are essential parameters for evaluating the productivity of shale gas wells. This study establishes new AOF calculation methods for the early production stage. The analytical model can calculate the AOF only by using stable pressure and production data in the flowback stage, which greatly improves the efficiency of productivity evaluation. Three methods have, respectively, calculated the productivity of the shale gas wells above 3500 m in the Luzhou block. The results show that well L2-3 has the highest AOF, averaging 278.1 × 10 4 m 3 / d , whereas well Y2-8 has the lowest AOF, averaging 100.2 × 10 4 m 3 / d . Different AOF calculation methods are identified for gas wells in different stages of production. For gas wells in the initial unstable flow stage, a pseudogas production index method is recommended. A water production index analysis method, with lower evaluation results, is proposed for gas wells in the flowback stage. A modern production decline analysis method is found to be preferred for calculating the EUR of deep shale gas wells. Well L2-3 has the highest average EUR of 1.26 × 10 8 m 3 , whereas well Y2-8 has the lowest average EUR of 0.42 × 10 8 m 3 . The Blasingame method is recommended for medium-to-high-production gas wells, whereas a normalized pressure integral method is suggested for low-production wells. A strong exponential quantitative link between the AOF and the EUR shows that a fracture system’s initial productivity has a significant impact on a well’s EUR. The findings of this study enrich the productivity evaluation system, increase the accuracy of productivity evaluation results, and provide theoretical support for deep shale gas wells.

Prediction Model of Bailing Oil Dynamic Production and Periodic Optimization

As a production method of low production wells and remote oil wells, bailing oil recovery is particularly important for its reasonable working system. The dimensionless bottom hole flowing pressure is solved by establishing the seepage mechanics equation of infinite homogeneous formation, and the productivity of bailed well is predicted by using the direct relationship between bottom hole flowing pressure and unit flow rate. On this basis, a mathematical model of the net income of bailing wells is established to determine a reasonable bailing period with economic benefits as the goal, and solve the problem that the oil bailing system relies on experience and lacks theoretical guidance.

Why high porosity but low-production wells occur in carbonate reservoirs: An explanation from the perspective of pore structure

High porosity but low-production wells exist in the Leikoupo Formation in the Sichuan Basin, China. The unclear explanation for this phenomenon has led to the failure of fracture development. We selected 15 cores from the study area based on the oil test data to investigate the cause from the pore structure perspective. The pore structures were studied via a variety of petrophysical experiments, which include conventional physical property analysis, casting thin section, nuclear magnetic resonance technique, and constant-rate mercury injection. The results indicate that the main explanation for the high porosity but low-production wells is that the larger pore-to-throat ratio makes for poor pore connectivity and more large pores and vugs are trapped. Movable fluid saturation can be significantly influenced by microscopic pore structure rather than physical parameters, which is positively affected by throat radius and negatively correlated with the pore-throat radius ratio, relative sorting coefficient, and tortuosity of the throat. The results provide a basis for the exploration of carbonate reservoirs from a microscopic perspective.

Dynamic Analysis of Wen 23 Gas Storage

Wen 23 Gas Storage is reconstructed from Wen 23 Gas Field of Zhongyuan Oilfield, it is an underground gas storage of exhausted gas reservoir type.Two injection production cycles have been run since the establishment of the database, and the third injection production cycle is about to be completed, this paper focuses on the sealing, connectivity and current operation status of Wen 23 gas storage and low production factors of low production wells. The current operation status of Wen 23 gas storage is summarized in order to provide some reference for the subsequent production and operation of the gas storage.

About the “Heat Shock” Phenomenon

At present, depletion and diminished performance of oil formations take place. Operation of low production wells is carried out using ESP units at the rate of max. 35 m3/per day under low suction pressure of centrifugal pumps. The drop of the centrifugal pump suction pressure below the saturation pressure leads to liberation of free gas in the pumped mixture. Operation of a centrifugal pump during pumping of gas-cut mixtures results in reduction of the ESP unit efficiency. The loss of the pump efficiency leads to the fact that the substantial part of energy is consumed on heating and temperature rise of the centrifugal pump. Operation of a centrifugal pump at elevated temperatures results in frequent faults of the ESP units and in salt deposition. In some cases, faults of the ESP units may occur out of the blue due to the uncontrolled heat release and temperature rise. Let us call a sudden uncontrolled heating of a centrifugal pump a “heat shock”. The pump failure as a result of a heat shock is normally classified as the “wrongdoing of the oil producing organization personnel”. This article addresses the possibility of detection and elimination of the “heat shock” moment - a sudden ESP failure. Solution of this problem will be useful for design engineering of the pump automatic control.

Cause Analysis and Comprehensive Treatment of Low Production Wells in Overseas River Oilfield

Cause Analysis and Comprehensive Treatment of Low Production Wells in Overseas River Oilfield

Optimization of fracturing parameters for tight oil production based on genetic algorithm

It is difficult to determine the main controlling factors of tight oil production. In addition to the problem of uncontrollable prediction accuracy, the numerical prediction model established by the main controlling factors will also make the correctly predicted low production samples lose the value of development. Applying the optimization algorithm with fast convergence speed and global optimization to optimize the controllable parameters in the high-precision numerical prediction model can effectively improve the productivity of low production wells with timeliness, and bring greater economic value while saving development cost. Using PCA-GRA method, the sample weight and the weighted correlation ranking results of parameters affecting tight oil production were obtained. Thereupon then the main controlling factors of tight oil production were determined. Then we set up a BP neural network model with by taking the main controlling factors as input and tight oil production as output. The prediction effect of the network was good and can be put into use. The results of sensitivity analysis showed that the network was stable, and the total fracturing fluid volume had the greatest impact on the production of tight oil. Finally, by using genetic algorithm, we optimized the fracturing parameters of all low production well samples in the field data. Combined with the fracturing parameters of all high production well samples and the optimized fracturing parameters of low production wells, the optimal interval of fracturing parameters was given, which can provide guidance for the field fracturing operation.

Coalbed Methane Industry Development Framework and Its Limiting Factors in China

The current average daily gas production of single coalbed methane (CBM) wells in China is less than 1,300 m3. The low production rate of CBM wells dramatically limits the sustainable development of the CBM industry in China. To promote CBM industry development, three universal geological factors, i.e., gas sources, channels, and driving force of the low production wells are analyzed, considering the various and complicated geological conditions of CBM reservoirs in China. Additionally, we find that the growth in proven CBM reserves should be greatly promoted as the CBM proven rate is only less than 3% by the end of 2020. The widespread CBM extraction mode based on depressurization via dewatering generates very limited effects in coal seams with notable deformation, high in situ stress, or little water. Therefore, a specific design of CBM development modes is proposed, according to the applicable geological conditions of different CBM development modes. It covers depressurization via dewatering, depressurization via stress release, and coal and CBM comining. Moreover, the regional governments play a key role in the development of the regional CBM industry, and favorable policies should be formulated to promote the multipoint development conditions across China. This study is concluded to provide a recommended development framework involving sustainable CBM production in China and its development processes.

Shale gas well productivity potential evaluation based on data-driven methods: case study in the WY block

Evaluating the productivity potential of shale gas well before fracturing reformation is imperative due to the complex fracturing mechanism and high operation investment. However, conventional single-factor analysis method has been unable to meet the demand of productivity potential evaluation due to the numerous and intricate influencing factors. In this paper, a data-driven-based approach is proposed based on the data of 282 shale gas wells in WY block. LightGBM is used to conduct feature ranking, K-means is utilized to classify wells and evaluate gas productivity according to geological features and fracturing operating parameters, and production optimization is realized through random forest. The experimental results show that shale gas productivity potential is basically determined by geological condition for the total influence weights of geologic properties take the proportion of 0.64 and that of engineering attributes is 0.36. The difference between each category of well is more obvious when the cluster number of well is four. Meanwhile, those low production wells with good geological conditions but unreasonable fracturing schemes have the greatest optimization space. The model constructed in this paper can classify shale gas wells according to their productivity differences, help providing suggestions for engineers on productivity evaluation and the design of fracturing operating parameters of shale gas well.