The productivity evaluation model and its application for finite conductivity horizontal wells in fault block reservoirs

It is very difficult to evaluate the productivity of horizontal wells in fault block reservoirs due to the influence of fault sealing.On the basis of the method of images and source-sink theory,a semianalytical model coupling reservoir and finite conductivity horizontal wellbore flow dynamics was built,in which the influence of fault sealing was taken into account.The distribution of wellbore flow and radial inflow profiles along the horizontal interval were also obtained.The impact of the distance between the horizontal well and the fault on the well productivity was quantitatively analyzed.Based on this analysis,the optimal distance between the horizontal well and the fault in banded fault block reservoirs could be determined.According to the field application,the relative error calculated by the model proposed in this paper is within ±15%.It is an effective evaluation method for the productivity of horizontal wells in fault block reservoirs.The productivity of the horizontal well increases logarithmically as the distance between the horizontal well and the fault increases.The optimal distance between the horizontal well and the fault is 0.25-0.3 times the horizontal well length.

A smart productivity evaluation method for shale gas wells based on 3D fractal fracture network model

The generation method of three-dimensional fractal discrete fracture network(FDFN)based on multiplicative cascade process was developed.The complex multi-scale fracture system in shale after fracturing was characterized by coupling the artificial fracture model and the natural fracture model.Based on an assisted history matching(AHM)using multiple-proxy-based Markov chain Monte Carlo algorithm(MCMC),an embedded discrete fracture modeling(EDFM)incorporated with reservoir simulator was used to predict productivity of shale gas well.When using the natural fracture generation method,the distribution of natural fracture network can be controlled by fractal parameters,and the natural fracture network generated coupling with artificial fractures can characterize the complex system of different-scale fractures in shale after fracturing.The EDFM,with fewer grids and less computation time consumption,can characterize the attributes of natural fractures and artificial fractures flexibly,and simulate the details of mass transfer between matrix cells and fractures while reducing computation significantly.The combination of AMH and EDFM can lower the uncertainty of reservoir and fracture parameters,and realize effective inversion of key reservoir and fracture parameters and the productivity forecast of shale gas wells.Application demonstrates the results from the proposed productivity prediction model integrating FDFN,EDFM and AHM have high credibility.

Mitigation of polycyclic aromatic hydrocarbons(PAHs)in roasted beef patties by cold plasma treatment and products quality evaluation

The cold plasma(CP)technique was applied to alleviate the contamination of polycyclic aromatic hydrocarbon(PAH)in this investigation.Two different CP treatments methods were implemented in the production of beef patties,to investigate their inhibition and degradation capacity on PAHs.With 5 different cooking oils and fats addition,the inhibition mechanism of in-package cold plasma(ICP)pretreatment was explored from the aspect of raw patties fatty acids composition variation.The results of principal component analysis showed that the first two principal components accounted for more than 80%of the total variation in the original data,indicating that the content of saturated fatty acids was significantly positively correlated with the formation of PAHs.ICP pretreatment inhibited the formation of PAHs by changing the composition of fatty acids,which showed that the total amount of polyunsaturated fatty acids decreased and the total amount of monounsaturated fatty acids increased.Sensory discrimination tests demonstrated there were discernable differences between 2 CP treated samples and the controls,utilization of the ICP pretreatment in meat products processing was expected to achieve satisfying eating quality.In conclusion,CP treatment degraded PAHs through stepwise ring-opening oxidation in 2 reported pathways,the toxicity of PAHs contaminated products was alleviated after CP treatment.

Evaluation of Potential Land Productivity in Wulushan, West China

The general situation of the total land resources in Wulushan, West China was studied by field investigations with the aid of a GIS software, called Region Manager. The current status of land use in Wulushan is described. The potential land productivity was evaluated by a fuzzy comprehensive method, We take each plot as a basic unit of evaluation on the basis of an index system of land resources in Wulushan which was developed from the investigation data. Evaluation of potential land productivity is the key part of land management. A guideline is presented in this paper for a proper utilization of the land resources and to develop the productive capacity of the land.

Shale gas production evaluation framework based on data-driven models

Increasing the production and utilization of shale gas is of great significance for building a clean and low-carbon energy system.Sharp decline of gas production has been widely observed in shale gas reservoirs.How to forecast shale gas production is still challenging due to complex fracture networks,dynamic fracture properties,frac hits,complicated multiphase flow,and multi-scale flow as well as data quality and uncertainty.This work develops an integrated framework for evaluating shale gas well production based on data-driven models.Firstly,a comprehensive dominated-factor system has been established,including geological,drilling,fracturing,and production factors.Data processing and visualization are required to ensure data quality and determine final data set.A shale gas production evaluation model is developed to evaluate shale gas production levels.Finally,the random forest algorithm is used to forecast shale gas production.The prediction accuracy of shale gas production level is higher than 95%based on the shale gas reservoirs in China.Forty-one wells are randomly selected to predict cumulative gas production using the optimal regression model.The proposed shale gas production evaluation frame-work overcomes too many assumptions of analytical or semi-analytical models and avoids huge computation cost and poor generalization for numerical modelling.

Evaluation of rope shovel operators in surface coal mining using a Multi-Attribute Decision-Making model

Rope shovels are used to dig and load materials in surface mines. One of the main factors that influence the production rate and energy consumption of rope shovels is the performance of the operator. This paper presents a method for evaluating rope shovel operators using the Multi-Attribute Decision-Making （MADM） model. Data used in this research were collected from an operating surface coal mine in the southern United States. The MADM model consists of attributes, their weights of importance, and alter- natives. Shovel operators are considered the alternatives, The energy consumption model was developed with multiple regression analysis, and its variables were included in the MADM model as attributes. Preferences with respect to min/max of the defined attributes were obtained with multi-objective opti- mization. Multi-objective optimization was conducted with the overall goal of minimizing energy con- sumption and maximizing production rate. Weights of importance of the attributes were determined by the Analytical Hierarchy Process （AHP）, The overall evaluation of operators was performed by one of the MADM models, i.e., PROMETHEE If. The research results presented here may be used by mining professionals to held evaluate the performance of rode shovel operators in surface mining.

Consumer Panel Size in Sensory Cosmetic Product Evaluation: A Pilot Study from a Statistical Point of View

Subjective evaluations are nowadays applied more commonly in cosmetic product assessment. They are used in quality control, product development steps and efficacy studies for claim support. Several studies have been published to determine the adequate number of panelists, but recommendations and guidelines dealing with this topic are rare in the cosmetic sector. The aim of the present pilot study was to recommend a suitable study plan and define the adequate consumer panel size for cosmetic consumer assessment. A questionnaire-based product evaluation study, with three different cosmetic products, was organized as a consumer test using a seven-point scale. As a last step, a specific statistical calculation was performed to define the minimum sample size. It showed that the minimum sample size, besides the obvious statistical parameters of standard deviation and confidence interval, also depends on age and gender of the panelists and product assessment item. Utilizing a CI of 95% a minimum of 60 panelists seems to be sufficient for home-use-test (HUT) with a given seven-point scale. A minimum of 101 panelists are shown to be sufficient utilizing a CI of 99%.

Study on the evaluation system for the cleaner production of the mine

It is important to establish the evaluation system of the cleaner production of the mining enterprise, which canprovide the technical support and guidance for the cleaner production evaluation and facilitating the promotion ofcleaner productive techniques so as to realize the integration of economic development and environmental protection.This paper, according to the characteristic of mining and Analytic Hierarchy Process (AHP), establishes the evaluationindex system, puts forward the overall quantitative evaluation method based on Fuzzy Mathematics and the experts’experience, and establishes the evaluation system of cleaner production. The main problems in cleaner production of themine are analyzed by calculation, and some countermeasures and suggestions are proposed.

Product Evaluation Knowledge Acquisition Based on Rough Sets

The method and steps of acquiring evaluation rules based on the knowledge reduction theory of rough sets is discussed, and the distilling process and approach for the evaluation rules of mechanical product structure design is described by using hydraulic torque converter as an example. Practice shows that this approach to a certain extent simplifies the knowledge base structure and reasoning process in comparison with the case-based reasoning method in the aspect of setting up evaluation rule base and carrying out reasoning to realize the mechanical product evaluation.

Optimization of integrated geological-engineering design of volume fracturing with fan-shaped well pattern

According to the variable toe-to-heel well spacing, combined with the dislocation theory, discrete lattice method, and finite-element-method(FEM) based fluid-solid coupling, an integrated geological-engineering method of volume fracturing for fan-shaped well pattern is proposed considering the geomechanical modeling, induced stress calculation, hydraulic fracturing simulation, and post-frac productivity evaluation. Besides, we propose the differential fracturing design for the conventional productivity-area and the potential production area for fan-shaped horizontal wells. After the fracturing of the conventional production area for H1 fan-shaped well platform, the research shows that the maximum reduction of the horizontal principal stress difference in the potential productivity-area is 0.2 MPa, which cannot cause the stress reversal, but this reduction is still conducive to the lateral propagation of hydraulic fractures. According to the optimized fracturing design, in zone-Ⅰ of the potential production area, only Well 2 is fractured, with a cluster spacing of 30 m and an injection rate of 12 m^(3)/min per stage;in zone-Ⅱ, Well 2 is fractured before Well 3, with a cluster spacing of 30 m and an injection rate of 12 m^(3)/min per stage. The swept area of the pore pressure drop in the potential production area is small, showing that the reservoir is not well developed. The hydraulic fracturing in the toe area can be improved by, for example, properly densifying the fractures and adjusting the fracture distribution, in order to enhance the swept volume and increase the reservoir utilization.

A new method to evaluate integrated production system capacity in oil fields

To improve the design and management of an integrated production system(IPS),a set of mathematical models and workflows are developed for evaluating the capacity of an IPS at steady-state conditions.Combining the conservation laws with applicable multiphase fluid and choke models,these mathematical models are solved to characterize the hydraulics of an integrated system of reservoir,wells,chokes,flowlines,and separator at steady state.The controllable variables such as well count,choke size and separator pressure are adjusted to optimize the performance of the IPs at a specific time.It is found that increasing the well count can increase the bulk flow rate of the production network,but too many wells may increase the manifold pressure,leading to decline of single-well production.Increasing the choke size can improve the capacity of the IPs.The production of the IPs is negatively correlated with the separator pressure.With increasing separator pressure and decreasing choke size,the increment of total fluid production(the capacity of IPS)induced by increasing well count decreases.Validation tests with field examples show a maximum absolute deviation is 1.5%,demonstrating the robustness and validity of the proposed mathematical models and workflows.

Application of Fluid Phase Recovery Method in the Early Development of BZ26-6 Volatile Oil Field in Bohai Sea

BZ26-6 Oilfield is a kind of deep metamorphic rock buried-hill volatile oilfield in Bohai Sea, China. Its early development plan is restricted due to the simultaneous production of oil and gas in large sections of reservoirs, unclear understanding of formation fluid properties and uncertainty of gas-oil interface. Through theoretical research on phase recovery and experimental analysis of crude oil phase characteristics in the original formation, characteristic parameters of the equilibrium condensate gas fluid are restored and calculated. Through the superimposed phase diagram of volatile oil and condensate gas, BZ26-6 Oilfield is determined to be a volatile oil reservoir with a condensate gas cap, with formation pressure and saturation pressure of 36.1 MPa, respectively. Based on the research results of oil-gas phase behavior characteristics, the thermodynamic equations and equation of state are jointly used to solve the problem, and the content change curves of each component at different depths are drawn. Combined with the sensitivity analysis of numerical simulation, the gas-oil interface is determined to be -3726 m above sea level. The fluid phase analysis software, Fluidmodeler, is used to simulate volatile oil degassing and condensate gas separation experiments. In combination with oil and gas production data obtained through the production test, the specific oil recovery index and the specific gas recovery index are determined to be 0.408 m3/(MPa·d·m) and 1195 m3/(MPa·d·m), respectively. And the reasonable production capacity prediction is conducted on the early development of BZ26-6 Oilfield. The research results can provide a theoretical basis for the efficient development of similar complex oil and gas reservoirs.

“Extreme utilization”development theory of unconventional natural gas

In the process of unconventional natural gas development practice,the"extreme utilization"concept that focuses on"continuously breaking through the limit of development technology"is gradually formed,and supports the scale benefit exploration of unconventional gas in China.On this basis,the development theory of"extreme utilization"is proposed,its theoretical connotation together with development technologies of unconventional natural gas are clarified.The theoretical connotation is that,aiming at"extreme gas reservoirs","extreme techniques"are utilized to build subsurface connected bodies,expand the discharge area,and enlarge the production range,to obtain the maximum single-well production,extreme recovery,and eventually achieve the"extreme effect"of production.The series of development technologies include micro/nano-scale reservoir evaluation,"sweet spot"prediction,unconventional percolation theory and production capacity evaluation,optimization of grid well pattern,optimal-fast drilling and volume fracturing,and working regulation optimization and"integrated"organizing system.The"extreme utilization"development theory has been successfully applied in the development of unconventional gas reservoirs such as Sulige tight gas,South Sichuan shale gas,and Qinshui coalbed methane.Such practices demonstrate that,the"extreme utilization"development theory has effectively promoted the development of unconventional gas industry in China,and can provide theoretical guidance for effective development of other potential unconventional and difficult-to-recovery resources.

Product Quality Evaluation Method Based on Product Gene Theory

Traditional quality inspection based product quality evaluation method with complex process has high operating cost and requires more professional knowledge. To remove the above limitation, this paper leads product gene theory into product quality evaluation. Methods of quality influencing factors based modeling and encoding are established. Combined with similarity theory and product gene theory, a product gene similarity analysis based quality evaluation method is proposed. The proposed method is low cost, operates easily and requires less specialized knowledge. A case study is conducted to prove the correctness and feasibility of this method.

Quantitative characterization of horizontal well production performance with multiple indicators: a case study on the Weiyuan shale gas field in the Sichuan Basin, China

To quantitatively characterize the horizontal shale gas well productivity and identify the dominant productivity factors in the Weiyuan Shale Gas Field,Sichuan Basin,a practical productivity method involving multiple indicators was proposed to analyze the production performance of 150 horizontal wells.The normalized test production,flowback ratio,first-year initial production and estimated/expected ultimate recovery(EUR)were introduced to estimate the well productivity in different production stages.The correlation between these four indicators was determined to reveal their effects on production performance forecasts.In addition,the dominant productivity factors in the present stage were identified to provide guidance for production performance enhancement.Research indicates that favorable linear relations exist between the normalized test production,first-year initial production and EUR.The normalized test production is regarded as an important indicator to preliminarily characterize the well productivity in the initial stage.The first-year initial production is the most accurate productivity evaluation indicator after a year.The flowback ratio is a supplementary indicator that qualitatively represents the well productivity and fracturing performance.The well productivity is greatly dependent on the lateral target interval,drilling length of Longmaxi1_(1)^(1)(LM1_(1)^(1))and wellbore integrity.The first-year recovery degree of EUR is 24%–58%with a P50 value of 35%.