Production Of Single Well Research Articles

Feasibility study on short radius sidetracking technology of old well in Hoja Gulluk Gas Field - A case study of H-1 well

The Hojaguruk block is located in the central and eastern region of the Amu Darya River. The reservoir is a hard carbonate reservoir with abnormally high pressure formation, which makes well control difficult. The reservoir is covered with a thick salt paste layer, and it is difficult to drill directional well in the salt paste layer. As the central and eastern parts of the right bank of the Amu Darya River enter the late stage of development, the production capacity of old lying Wells is insufficient and the reservoir energy power is reduced. Therefore, it is urgent to transform old Wells with short radius sidetracking drilling technology and revive lying Wells to improve the production of single well and achieve the goal of stable production and increase production. Based on a comprehensive analysis of the geological characteristics, development situation and technical difficulties of short radius sidetracking in the area where well H-1 is located, this paper analyzes and demonstrates the determination of the cutting point of sidetracking technology, the optimization of the well trajectory design scheme and the analysis and demonstration of the ultra-short radius sidetracking technology, and considers all factors comprehensively to study and determine that the ultra-short radius sidetracking technology is suitable for this well condition. It can meet the requirements of reservoir development design. It is suggested to carry out the key test of the ultra-short radius sidetracking technology, and promote the application in the developed blocks in the central and eastern part of the Amu Darya Project, so as to provide research ideas and directions for tapping the potential operations in other blocks.

A production prediction method of single well in water flooding oilfield based on integrated temporal convolutional network model

Since the oil production of single well in water flooding reservoir varies greatly and is hard to predict, an oil production prediction method of single well based on temporal convolutional network (TCN) is proposed and verified. This method is started from data processing, the correspondence between water injectors and oil producers is determined according to the influence radius of the water injectors, the influence degree of a water injector on an oil producer in the month concerned is added as a model feature, and a Random Forest (RF) model is built to fill the dynamic data of water flooding. The single well history is divided into 4 stages according to its water cut, that is, low water cut, middle water cut, high water cut and extra-high water cut stages. In each stage, a TCN based prediction model is established, hyperparameters of the model are optimized by the Sparrow Search Algorithm (SSA). Finally, the models of the 4 stages are integrated into one whole-life model of the well for production prediction. The application of this method in Daqing Oilfield, NE China shows that: (1) Compared with conventional data processing methods, the data obtained by this processing method are more close to the actual production, and the data set obtained is more authentic and complete. (2) The TCN model has higher prediction accuracy than other 11 models such as Long Short Term Memory (LSTM). (3) Compared with the conventional full-life-cycle models, the model of integrated stages can significantly reduce the error of production prediction.

Research and application of large-scale fracturing imitating horizontal well technology in vertical well

Hailaer Basin is rich in geological reserves, but the proportion of undeveloped reserves is high, accounting for 30% of the proved reserves. In order to improve the production degree of reserves and single well production, and realize the purpose of high and stable production of the oilfield. Taking the ultra-low permeability reservoir of oilfield B in Hailaer Basin as an example, this paper puts forward the large-scale fracturing of vertical wells and water injection development technology of imitating horizontal wells. By forming directional ultra long fracturing fractures in the oil layer, this technology can effectively increase the reservoir conductivity, increase the oil well drainage area and water well control area, reduce the well pattern density and improve the production of single well. The research shows that the undeveloped reserves in Hailaer oilfield have the characteristics of low thickness, low permeability and low reservoir quality index. There are 55 large-scale mold fracturing wells in Hailaer oilfield, with an initial oil increase of 2.2 times. The sand amount of large-scale fracturing is 2.5 times that of ordinary fracturing, and the fluid amount and sand intensity are 4.5 times that of conventional fracturing. The vertical well large-scale fracturing imitating horizontal well technology is adopted in Oilfield B. The designed vertical well fracturing fracture is 600m long and 120m wide, and the production effect is good after fracturing. The research results are of great significance to the high and stable production of undeveloped reserves block in Hailaer oilfield and other similar oilfields.

Development and Application of Efficient Oil Displacement System for Middle-Low Permeability and High Pour-Point Heavy Oil Reservoirs

In view of the problems of low permeability, high oil viscosity and freezing point, and low productivity of single well in Luo 321 and Luo 36 blocks of Luojia Oilfield, the chemical viscosity-reducing cold production technology was studied. By analyzing the properties of crude oil, it is concluded that the reason for high viscosity and high freezing point is the high content of asphaltene, pectin, and wax. The viscosity is mainly affected by asphaltene; the wax precipitation point and pour point are mainly affected by the wax; and the solidification point is affected by the wax and asphaltene. The treatment idea of reducing viscosity and inhibiting wax is determined. By compounding the synthetic pour point depressant POA-VA and the viscosity reducer DBD-DOPAMA, the effect of reducing the viscosity and freezing point of crude oil was evaluated. PD-7 (POA-VA 40%, DBD-DOPAMA 50%, and P-10C 10%) system was selected as the optimal formula. When the concentration of the system is 10%, the viscosity reduction rate reaches 95.2%; the freezing point can reduce by 10.2°C; it has good oil sample adaptability, salinity resistance, and temperature resistance; and the oil washing rate can reach more than 60%. The oil displacement system was injected into the formation by means of multiconcentration and multislug and was applied in the field of Luo 321-2 Well. A total of 500 t of the oil displacement system was injected, and the effect of measures lasted for 400 days, with a cumulative oil increase of 883 t. It has been applied in different blocks 30 times and achieved a good field application effect.

The experimental study on the coal rock breaking efficiency of the self-rotating multi-orifice nozzle applied in URRS technique

China has abundant coalbed methane (CBM) reserves, but the production of single well is rather low. The Ultra-short Radius Radial System (URRS) technique can drill multiple radial branch holes with hydraulic jetting to effectively improve the production of single well. The high-pressure jet nozzle plays an important role in URRS technique and the structure of nozzle directly affects the efficiency of radial drilling. This paper adopts the experimental study on breaking coal rock efficiency of the self-rotating multi-orifice nozzle with different structures. The uniaxial compressive strength, tensile strength and shear strength of experimental rock samples were tested and calculated. Using natural coal and briquette rock, number of experiments under submerged conditions were carried out. The effects of nozzle pressure, jetting distance, jetting time and jetting direction on rock breaking effect were studied. The experimental results show that natural coal rock has strong anisotropy and demonstrate the coal rock breaking efficiency of the self-rotating multi-orifice nozzle. The key findings are expected to provide theoretical and technical support for development of CBM reserves by using the URRS technique.

High-efficiency fracturing technology and application on CBM horizontal wells in Qinshui Basin

L-type horizontal well has became a new well type for CBM development in Qinshui Basin, And the staged fracturing technique of horizontal well is the key technology to improve gas production of single well for coalbed gas. At present, the main fracturing technology of horizontal well is the fracturing technology of tubing carrying a packer at the bottom, and daily gas production of it exceed 10000 cubic meters in Zhengzhuang with ultra-low permeability. And the average daily gas production of a well is more than 6000 cubic meters. In recent years, we have gradually explored different fracturing technologies, containing plug-perforation joint fracturing, coiled tubing fracturing and staged fracturing of spray gun with expanding diameter. Taking the L-type horizontal wells of the casing fracturing in Qinnan as the research object, the adaptability analysis and the evaluation of development effect of four fracturing technologies, including the fracturing of common tubing carrying a packer at the bottom, the fracturing of spray gun with expanding diameter, plug-perforation joint fracturing and coiled tubing fracturing, are carried out. The analysis results show that the fracturing technology of tubing carrying a single packer at the bottom has the advantages of simplicity, low price and good effect on development, which can be used as the main technology of the L-type horizontal wells of the casing fracturing.

Economic feasibility evaluation of shale gas stratified development in Chongqing area

Shale gas as a clean green energy has been rapidly developed in China. At present, the vertical production rate of shale gas in Chongqing area is low, and it is difficult to take into account the whole highquality shale segment with thickness of tens of meters only by one well pattern. In this paper, the internal rate of return (IRR) is used to calculate the impact of different costs and exploitation conditions on the development effect of two shale gas layers. The results show that shale gas development will be profitable only when the cost per well is controlled at around 70 million and production is provided at more than 100 million cubic meters. Domestic producers should further reduce the cost of shale gas development, increase the productivity of single well and maximize the benefit of domestic shale gas development by means of integrated innovation and technological optimization.

Hydraulic Fracturing Characteristics and Stimulation Optimization of Tuffaceous Sandstone Reservoir in San Jorge Basin, Argentina

According to the post fracturing production performance characteristics of the operation wells in Sinopec Argentina work area of San Jorge basin, the more intensive the reconstruction is, the worse the effect is. By comparing the characteristics of typical wells, combining with the distribution characteristics of reservoir, the influence of tuffaceous matter, the state of in-situ stress, and the propagation law of hydraulic fractures, the main factors causing the abnormal performance are revealed. The characteristic parameters of typical wells in the work area are compared, and the main control factors affecting the key parameters of production are discussed. From the fracture scale, working fluid system, pumping parameters and other aspects, the targeted measures are optimized. The practice shows that the success rate of low intensity transformation is higher, which is nearly 10% higher than that of medium intensity transformation; within one year after fracturing, the average daily oil production of single well is 3.0 m³ higher, and the efficiency is remarkable. According to the characteristics of the work area, the small-scale and low-intensity sand adding transformation scheme is adopted, which improves the success rate and efficiency of hydraulic fracturing operation, and provides a new technical idea for tapping the potential of the next process.

CO2-prepad injection EOR simulation and sensitivity analysis considering miscibility and geomechanics in tight oil reservoirs

Injecting CO2 pre-pad into tight reservoirs before hydraulic fracturing is a promising way to improve the productivity of single well. In this method, CO2 should be injected into the formation at a high rate. Also the miscibility of CO2 and oil with the changes of intricate geomechanics during this process are complex. Meanwhile, the geological and operating parameters have a dramatic influence to oil production and is lack of systematic research. In this study, a fluid model of crude oil was established to evaluate the impact of CO2 on oil volume and viscosity. Then, a compositional numerical model coupled miscibility and geomechanics were set up to analyze enhanced oil recovery (EOR) potential under different miscible degree with in-situ stress field. Ultimately, in accordance with multiple nonlinear regression production forecast models, Sobol, FAST (Fourier Amplitude Sensitivity Test), and DGSM (derivation-based Global Sensitivity Measure) methods were utilized to study the main factors affecting cumulative production. The results shown that CO2 almost has the same effect on the volume of these tight oil and has the most significant effect on the viscosity of crude oil we studied by comparing. The production of miscible flooding is 38.2% and 16.4% higher than that of immiscible and near-miscible flooding, respectively. The formation were compacted during production especially in the early stage, hence the production of the model with geomechanics was 23.3% less than the model of non-geomechanics. The first-order sensitivity indexes of bottom-hole flow pressure, reservoir thickness and fracture conductivity are about 0.808, 0.176 and 0.004 respectively obtained by Sobol method, consistent with two other methods. This result shows that bottom-hole flow pressure, reservoir thickness and fracture conductivity are the most important factors affecting production, and bottom-hole flow pressure has the most significant impact on production. This work investigates how miscibility and geomechanics effect on production as well as clarified the factors affecting production for CO2 pre-pad injection, providing vital insights into operating in tight reservoirs for oil field.

Pore Structure Characteristics of Ultra-Low Permeability Reservoirs

Pore structure characteristics of ultra-low permeability reservoirs are studied in this paper. The impact of pore structure characteristics on permeability and reservoir development effect is analyzed by conventional and constant-rate mercury penetration experiments. The results show that the frequency curve of pore radius distribution of ultra-low permeability reservoirs has little change with permeability. The average pore radius in ultra-low permeability reservoirs with different permeability levels had little difference, and its distribution ranges from 98.5 to 110.1 μm. With decrease of permeability, the frequency distribution curves of throat radius and pore-throat ratio change significantly. The peak value of throat radius curve moves to the left and increases significantly, and the average throat-radius distribution decreases from 2.33 to 0.91 μm. However, the impact of pore-throat ratio on permeability is contrary to that of throat radius. Both throat radius and pore-throat ratio has strong correlation with permeability, and they are in exponential relationship. With the in-depth study, it is found that seepage capacity of reservoirs is restricted mainly by throat radius and pore-throat ratio. When throat radius decreases to less than 1 μm and pore-throat ratio increases more than 130, permeability decreases sharply and obviously. When permeability is less than 2 × 10−3μm2, the proportion of fine throats and medium throats under the condition of effective water injection is significantly lower, and the production of single well and the recovery efficiency by water flooding in ultra-low permeability reservoirs are low. The study explains effectively the fundamental reason for the poor efficiency of production and recovery of ultra-low permeability reservoirs from the mechanism.

Application of rock brittleness evaluation in tight oil exploration—— Taking Lijiaweizi Fault Depression in Qijia Area as an Example

Brittle rock is one of the key factors in the use of unconventional oil and gas exploration technology to be considered, The stronger the brittleness of rock is, the easier to produce fractures to form fracture network in the over flushing of fracturing, the stock of oil and gas storage layer will be increased, and the production of single well will be increased. At present mainly based on rock elastic parameters, we use Young’s modulus and Poisson’s ratio of two ways to analyze brittle rock in earthquake prediction evaluation. However, since these two methods in the process, both the need for elastic parameters of rock normalized, leading to large errors, adaptability reduce. Based on this, we propose a Young’s modulus and Poisson’s ratio coefficient of utilization of compared to the brittle rock evaluation method to effectively improve the accuracy of prediction and evaluation of brittle rock and anti-jamming capability, while the brittle evaluation method based on the use of pre-stack seismic inversion of elastic parameters to Qijia area of Songliao basin compact oil brittle rock predict deployment guidance wells to obtain stable high level of industrial oil flow.

Optimization of Trajectory Design for Highly Deviated Directional Wells

Highly deviated directional well technology has the advantages of drilling through longer shale gas reservoir section, detecting and controlling gas bearing area in a large range, and greatly improving gas production of single well. Based on the preliminary work of vertical well and pre exploration well, through the optimization design of well bore structure, well trajectory, BHA, drill string mechanics, drilling fluid, cementing and other technologies, the drilling engineering design scheme of high angle directional well in accordance with shale gas exploration in high steep structural area is optimized, and the formation pressure profile and bit selection scheme are established to form a set of drilling technology for efficient development of shale gas The technology system can be used for reference for the exploration and development of shale gas and coalbed methane in other areas in the future.

Study on the dosage of temporary plugging Agent for steering fracturing

The Triassic Baikouquan Formation in the Junggar Basin has developed a large number of dense sandstore conglomerate reservoirs, which belong to ultra-low permeability and ultra-low permeability refractory reservoirs. In recent years, the productivity of single well is improved by selecting potential production wells for multi-stage steering fracturing. In order to realize the forced steering of fractures, it is very important to study the sealing pressure of temporary plugging agent. According to the actual needs of Baikouquan steering fracture, the net pressure model of steering fracture is established. The net pressure value in the seam is calculated according to the change of ground stress after steering, then calculated the minimum temporary plugging agent sealing pressure needed for a single fracture. Based on the net pressure model, the corresponding software is developed and applied to the field. The practical application effect is good, which provides economical and effective technical technical support for the continuous and stable production of low permeability oil field.

Analysis of Factors Affecting Productivity of Horizontal Wells Based on Grey Relational Theory

Taking Bp block of the Middle East as the target, on the basis of Joshi’s formula of horizontal well productivity prediction and the application of grey relevancy analysis on the average permeability, effective thickness, production pressure difference, oil saturation of reservoir and other major factors for the impact of the initial productivity of the horizontal wells, by means of obtaining the grey relational grade of influencing factors and the production of single well and optimal to optimize the combination of differential pressure, horizontal section length and other parameters, the effective exploitation of the oil field is achieved.

Study of Cyclic Fracturing in Vertical CBM Wells

Background:Coal-bed methane productivity of single well is very low, and has been the bottleneck of the coal-bed methane industry in China.Objective:Although hydraulic fracturing is the only stimulation measure to develop CBM, it cannot increase production effectively, conventional fracturing method to create opening fractures should be improved. How to make good use of natural fractures, which are plentiful in CBM reservoirs, is also an important subject for hydraulic fracturing.Method:In this paper, the plastic deformation of coal rock is analyzed by harnessing a pseudo-Maxwell creep phenomenon, which is normally present in rock. The Kelvin-Voigt model is utilized to describe pseudo-plastic behavior of coal rock to determine pressurization and decay cyclic time for cyclic fracturing design. The mechanical requirement for shearing natural fractures is also analyzed, and shearing distance between the faces of natural fracture can be calculated by Westergaard stress function. Ultimately, the cyclic fracturing method is proposed according to theories about stress alteration and shearing of natural fractures. This method includes such periods as fracturing, pumping shut-down and so on.Conclusion:A complex fracture system can be created, which consists of opened and sheared fractures, then, large SRV(stimulated reservoir volume)and flowing drainage area can be acquired. In comparison with conventional fracturing method, this new way can make full use of the characteristics of CBM reservoirs and is more suitable to CBM. This method will lead to a significant increase of CBM production, and will achieve huge economic benefits.

An interwell connectivity inversion model for waterflooded multilayer reservoirs

Abstract In view of the limitations that the current connectivity model can only forecast the fluid production dynamic change, can't calculate the dynamics of oil and water phases, and can't analyze the connectivity between wells layer by layer, this study establishes a new interwell connectivity model for multilayer reservoirs which can simulate dynamics of oil and water between wells. The model hierarchically separates the reservoir system into a series of interwell connecting units characterized by parameters such as conductivity and control volume, and by using the material balance equation, the pressure and interwell flow at constant liquid production or constant pressure mode is calculated regarding the connecting unit as a simulation object, which are combined with the frontal advance theory to establish interwell saturation tracking calculation, and finally water production dynamics of every layer at well points can be worked out. On this basis, using simultaneous perturbation stochastic approximation method and gradient projection method, a model parameter inversion method is set up by dynamic fitting. The application cases show that the model has good dynamic fitting and prediction effect, inversed model parameters coincide with the actual geological parameters, verifing the validity of the method. Compared with the current connectivity method, it can obtain the real-time model of hierarchical interwell flow rate distribution coefficient, liquid production of single well and oil split coefficient and other information, and reflect the reservoir horizontal and vertical oil-water flow relation more accurately, providing guidance for production measure adjustment in oilfield.

Comprehensive Analysis of Factors Affecting Coalbed Methane Productivity: A Case Study of Southern Qinshui Basin

Coalbed methane (CBM) productivity is influenced by various factors. Based on field production data and test data of southern Qinshui Basin, factors including geological factors, engineering factors and drainage factors that affect CBM productivity are analyzed. Analytic hierarchy process (AHP) is introduced to calculate the contribution of each parameter to CBM productivity. A three-level model for evaluating CBM productivity based on AHP is established. The results show that average daily gas production of single well in southern Qinshui Basin increases with gas content, coal seam thickness, permeability, porosity, gas saturation, critical desorption pressure. Filling minerals in pores and fractures of coal can decrease gas content, porosity and permeability of coal reservoir. When burial depth is deeper than 500m or reservoir pressure is greater than 2MPa and burial depth is shallower than 1000m or reservoir pressure is less than 10MPa, CBM productivity is relatively high. According to the calculation, the weight of geological factors, engineering factors and drainage factors are 50%, 25% and 25%, respectively. Reservoir physical properties, geological conditions, fracturing technology and drainage process have the most impact, the weight of which are 33.33%, 16.67%, 11.79%, and 15.00%, respectively.

Superiority of Superheated Steam Flooding in Development of High Water-Cut Heavy Oil Reservoir

The dryness of superheated steam is 100% and it exists in the form of pure steam whose properties are like ideal gas. When the steam has a large degree of superheat, it may take a relatively long time to cool, during which time the steam is releasing very little energy and transmitted long distances. The heating radius of superheated steam in the formation is 5-10m larger than saturated steam. In the heating area of superheated steam, the comprehensive effects by superheated steam (crude oil viscosity reduction, improved flow environment, changes in rock wettability and improved oil displacement efficiency, etc.) is much higher than that of saturated steam. Superheated steam stimulation in Kenkyak high water cut heavy oil reservoir pilot test results showed that the average daily oil production of single well by superheated steam stimulation was 2-4 times than that of saturated steam stimulation. Superheated steam is more effective to heat water-invaded oil reservoir than saturated steam.