Continuous Gas Lift Research Articles

Optimizing gas lift for enhanced recovery in the Asmari formation: a case study of Abu Ghirab field in Southeastern Iraq

The gas lift technique applies gas bubble injection into the vertical wells to raise production. Gas and liquid rates, shifts in flow regimes, and system equilibrium influence this process. This study explores the efficient implementation of gas lift techniques to maximize production from the Asmari Formation in the Abu Ghirab Field, southeastern Iraq, using a continuous gas lift for maximum production rate by PIPESIM TM software. The results of the gas lift design for the four wells (AGCS-33, 26, 28, and 36) show that the Vogel method provided the best results for the gas lift design, and faults and facies distribution impact the gas lift injection and oil production rates. These will become evident with wells AGCS-33 and 36 as their proximity to faults will increase oil production rates with a gas injection rate limit of 7 MMSCF/d. Conversely, for wells 26 and 28, the limit will marginally rise, starting at 5 MMSCF/d. In addition, the effect of gas lift is clearly in the middle western of the crest, which shows an increasing percentage of oil production of 136.6% at minimum rate and 198.5% at maximum for the well AGCS-26, 89.7% and 105.7% for the well AGCS-36. Wellhead pressure has a significant impact on gas-lift performance, and improving gas-lift efficiency can be accomplished using an electric control valve. The feasibility of implementing gas lift in the Asmari Formation depends on the water cut, well location, and water saturation distribution within the Formation.

Gas Lift Optimization for Zubair Oil Field Using Genetic Algorithm-Based Numerical Simulation: Feasibility Study

The gas-lift method is crucial for maintaining oil production, particularly from an established field when the natural energy of the reservoirs is depleted. To maximize oil production, a major field's gas injection rate must be distributed as efficiently as possible across its gas-lift network system. Common gas-lift optimization techniques may lose their effectiveness and become unable to replicate the gas-lift optimum in a large network system due to problems with multi-objective, multi-constrained & restricted gas injection rate distribution. The main objective of the research is to determine the possibility of using the genetic algorithm (GA) technique to achieve the optimum distribution for the continuous gas-lift injection flows in the structure of the network of Zubair, oil field with 10 gas-lift injected wells. This will be done through numerical simulation and modeling studies. The overall enhancement of the filed production rate is found to have increased from 15767 STB/day to 19847 STB/day. The well's reservoir pressure and water cut sensitivity studies are carried out to study the possible impacts of these elements upon the well and its efficiency through the course of the field. Our understanding of the potential benefits of utilizing gas lift techniques in a field from a technical and economical point of view is deepened by the use of examples from economic analysis. Furthermore, even though the idea of employing GA in this manner is not new, this work discusses GA-based optimization methodologies for increasing the oil production rate by using gas lifting in a Zubair oilfield. In order to assign gas injection rates to specific wells in a network throughout the field using limited gas injection rates, the model for optimization will be laid out step-by-step making it simple to understand and employ as a guide, especially for the front-line production technicians involved in the development and design of gas-lift systems.

Maximizing Production Profits: Optimizing Gas Lift Design in the Halfaya Oil Field

Gas lift is one of the most common artificial lift methods which is effectively utilized in the oil industry for enhancing production. However, proper gas allocation into wells can be challenging due to various limitations such as shortage in injected gas and economic considerations. Therefore, the current research is conducted to address the critical requirement to effectively distribute gas to maximize profits in the Halfaya Oil Field- Mishrif formation. Continuous gas lift is one of the most commonly used artificial lift methods. To enhance production rate, a sufficient amount of gas is injected into the production tubing at specific depths to reduce the liquid column pressure as each well has an optimal point for production in an oil reservoir. On the other hand, constraints of gas availability restrict achieving the optimal state of production. Such restrictions combined with economic limitations including high gas prices and compression costs, emphasized the necessity for optimal methodology to enhance oil production. Aside from the importance of the Halfaya oil field, there are limited relevant studies on artificial lifting methods specifically associated with the gas-lifting method used in this paper. Thus, the purpose of the current investigation is to propose a well-tested gas lifting design for oil production improvement. The approach combines the skill of the fmincon function built in MATLAB as an optimizer and the PIPESIM network model to create gas lift performance curves. This resulted in an oil production rate of 18860 STB/d, with a gas lift rate of 9.42 mmscf/d. Establishing such a systematic optimization process can manage the challenges of gas allocation in the Halfaya Oil Field towards maximizing production rates and ultimately increasing net profits.

A simulation model for oil production by intermittent gas lift technology

The operating principle of the oil production by intermittent gas lift (IGL) technology and the mechanical processes occurring in it are complex with many different stages and many flows interacting with each other in each stage. This leads to many difficulties in calculating and optimizing oil well production system with IGL technology. This study develops a hydrodynamic simulation model of the flows occurring during oil production by IGL. By improving until now published hydrodynamic simulations the model in this work is developed based on changes/adjustments to be applicable for specific field conditions. Simulation of the IGL process is performed based on numerical solutions of the systems of conservation equations of mass and momentum and closure equations for each system component and each stage of the IGL process. The ordinary differential equations in the model are solved by the implicit Euler method. The simulation program has been developed and used in selecting a reasonable design of IGL technology for an oil well previously produced by the continuous gas lift (CGL). After the IGL system was installed and put into operation, the daily liquid production rate of the well increased by 91% and the measured data showed good agreement with the simulated results. The application result has initially demonstrated the applicability of the proposed model and the developed simulation program. Keywords: well; intermittent gas lift; simulation model; oil production.

Solutions to increase the C-2P well production performance at X oil field, Block 09-2

The well C-2P had its first oil production in July 2008, the initial production rate is 3,000 barrels/day. Due to the reservoir pressure depletion in 2017-2018, the well faced difficulties in kicking off to open the well for production. In November 2018, when the C-5PST2 well was put into production, the C-2P well was not produced by natural flowing. The kicking off has been attempted many times but the well still won't flow. The main reason the well couldn’t flow is due to low reservoir pressure which has not enough energy to push all the fluid in the well to the surface after each well shutdown. The flow assurance study shows, at the reservoir pressure of 3,000 Psi, and tubing head pressure of 950 Psi, the well can’t flow naturally. In addition, with the reservoir pressure of 3,000 psia and applying the gaslift injection rate of 1.0 MMscf/d, injection point at 3,030 mTVD, the well flowed. The continuous gaslift pump helps maintain the well's production in case the reservoir pressure drops even lower to 2,000 psi, and at the same time, optimizing the gaslift pump flow helps to increase the well production by 100-300 barrels of oil/day. When the reservoir pressure drops lower, it is necessary to lower the gaslift valve deeper to continue kicking off the well and maintain the well production performance. On the other hand, due to the lack of a gaslift valve for the original design of C-2P well so it's necessary to have gaslift tubing pack off in order to bring the well back to production, maintain stability and improve production. This paper, therefore, presents the results of the research on the solution to increase the production output of the C-2P well located in X oil field used gaslift valve combining with the tubing pack off. Results of the research on the application of solution show that the well's production output has increased significantly (0.354 million barrels) in the first year of applying the solution.

The Water Problems and Treatment Strategies of Volcanic Gas Reservoir in Daqing

In order to realize the development strategy of “stabilizing oil and increasing gas and simultaneously boosting oil and gas”, Daqing Oilfield has continuously strengthened the exploration and development of deep natural gas resources since the discovery of Xushen gas Field. The volcanic gas reservoir is the main gas producing area of Songliao Basin. Through “internal excavation and external expansion”, natural gas production has maintained a trend of growth for 12 consecutive years. However, due to the development of fractures and bottom water in volcanic gas reservoir, the development contradiction caused by gas well water is increasingly prominent as the gas field development enters the end of stable production stage. Therefore, on the basis of the understanding of four types of effluent water in volcanic rock reservoir, this paper carries out the analysis of the production dynamic characteristics of typical gas wells, and identifies the difficulties faced by gas wells with different types of effluent water. Through field tests, economic and feasible treatment measures are explored, including continuous circulation gas lift of strong water breakthrough gas well in fracture vertical direction, intelligent foam drainage gas production of weak water breakthrough gas well in fracture vertical direction, and deep water unlocking of gas well in pore vertical water cone and gas reservoir with high water saturation gas reservoir effluent water, which provides technical support for the sustainable and efficient development of volcanic gas reservoir.

Sensitivity analysis for enhancing crude oil recovery with continuous flow gas lift: A study in reference to the porous media of the upper Assam basin, India

Despite minimal formation damage or water-cut, the majority of oil wells in brown oil fields cease to flow naturally. The current study looks into and analyses what caused a self-flowing well in the upper Assam basin to become non-flowing. The non-flow condition of the well was investigated in the current work as a function of water cut, reservoir pressure, reservoir rock permeability, and GOR. The effect of WHP and WHT on these functions was investigated. This work incorporates innovative methodology that uses the PROSPER simulation model for assessing the possibility of establishing flowability in a dead well based on inflow (IPR) and vertical lift performance (VLP). Subsequent analysis was carried out to examine the scope of producing this dead well under continuous flow gas lift. For this, the current work first examined the tubing diameter and reservoir temperature as standalone parameters to find out if they have any role to play in the flowability of the dead well. Following this, sensitivity analysis was done taking four parameters into account, i.e., reservoir pressure, reservoir rock permeability, water cut, and total GOR. In the current work, surface equipment correlation was established using Beggs and Brill correlation, while vertical lift performance was established using correlation from Petroleum Expert. The results of the current work highlight that a well's production rate under continuous flow gas lift can be enhanced by employing an optimised gas injection rate. The findings of this work conclude that higher reservoir pressure enables an oil well to produce with a high water cut under a continuous flow gas lift system, provided there are no formation damage issues on the well.

Analysis of crude oil production with gas lift methods

Some wells in the Niger Delta area are in their late production life. Water production increases with and reservoir pressure decreases to the point that the natural energy cannot sustain the production of hydrocarbon to the surface. The severity of this impact has been observed in the Niger Delta oil fields over the past years that has caused the abandonment of wells with a significant volume of hydrocarbon unrecovered. To increase production and extend the life of these wells, a gas lift project is considered. This study aimed to analyze oil production between continuous and intermittent gas lift systems based on real data obtained from two oil wells in a Niger Delta oilfield and to choose the system best suited to increase the production of the wells. To achieve this aim, a simulation study on continuous and intermittent gas lift methods was conducted using GAP and PROSPER software. The results obtained indicated that a continuous gas lift system will be suitable for a well that has a high flow rate and high GOR (well 1). For Well 2, the results indicated that an intermittent gas lift system will be suitable for a well that has lower reservoir pressure and low productivity.

Fuzzy controllers applied for management of choke opening in the continuous gas-lift systems

Fuzzy controllers applied for management of choke opening in the continuous gas-lift systems

Design of continuous gas-lift for a dead well and step-up of its productivity

The present paper aims to design a continuous gas-lift system in order to activate the dead well X and optimise the recovery of hydrocarbons by gas injection. The data taken into account are those of the reservoir and the well. All the simulation operations and the well diagram are carried out with the PIPESIM 2017 2.0 software. Moreover, the nodal analysis of the dead well X is carried out by finding the injection pressure of the gas in the well. The number of valves to be installed, the optimal injection heights and the flow rates received by each valve are also included in the gas-lift device. Then the evaluation of the system performance as well as the sensitivity analysis are carried out to make it possible to fix the optimal flow rate of production. The results obtained show that for a continuous gas injection of 3 million standard ft3 per day (MMscf/d) per valve into the well with a wellhead pressure of 2,500 psi and an optimal flow rate of 2,718 standard barrels per day (STB/d), a profitability of USD 182,887,219 is obtained. In this field, this design can be applied to all wells having a production tube of 2.5 inches inside diameter. On the other hand, wells with different diameters will require a new evaluation.

Application of artificial neural network for predicting production flow rates of gaslift oil wells

In petroleum industry, the prediction of oil production flow rate plays an important role in tracking the good performance as well as maintaining production flow rate. In addition, a flow rate modelling with high accuracy will be useful in optimizing production properties to achieve the expected flow rate, enhance oil recovery factor and ensure economic efficiency. However, the oil production flow rate is traditionally predicted by theoretical or empirical models. The theoretical model usually gives predicted results with a wide variation of error, this model also requires a lot of input data that might be time-consuming and costly. The empirical models are often limited by the volume of data set used to construct the model, therefore predicted values from the applications of these models in practical condition are not highly accurate. In this research, the authors propose the use of an artificial neural network (ANN) to establish a better relationship between production properties and oil production flow rate and predict oil production flow rate. Using production data of 5 wells which use continuous gas lift method in X oil field, Vietnam, an ANN system was developed by using back-propagation algorithm and tansig function to predict production flow rate from the above data set. This ANN system is called a back-propagation neural network (BPNN). In comparison with the oil production flow rate data collected from these studied continuous gas lift oil wells, the predicted results from the constructed ANN achieved a very high correlation coefficient (98%) and low root mean square error (33.41 bbl/d). Therefore, the developed ANN models can serve as a practical and robust tool for oilfield prediction of production flow rate.

Numerical Simulation of Gas Lift Optimization Uses Genetic Algorithm

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper IPTC 20254, “Numerical Simulation of Gas Lift Optimization Using Genetic Algorithm for a Middle East Oil Field: Feasibility Study,” by Mustafa AlJuboori and Mofazzal Hossain, SPE, Curtin University, and Omar Al-Fatlawi, SPE, University of Baghdad, et al. The paper has not been peer reviewed. Copyright 2021 International Petroleum Technology Conference. Reproduced by permission. Optimal allocation of gas-injection rates in large fields through a gas lift network is a challenging task. Traditional gas lift optimization programs may prove inefficient or incapable of modeling gas lift optimization in extremely large networks. The key objective of the complete paper is to assess the feasibility of using the genetic algorithm (GA) technique to optimize the allocation of continuous gas lift injection rate in a network of a Middle Eastern oil field with 43 gas lift injected wells through numerical modeling and simulation studies. GA GA is an optimization technique that solves constrained and unconstrained optimization problems through a natural-selection process based on the concept of evolutionary biology, including the fundamental processes of selection, crossover, and mutation. Instead of considering a single point or solution, a population of solutions is designed. The algorithm modifies the population of individual solutions repetitively, selects individuals randomly from the current population as parents, and uses these parents to produce the children for the next generation. The population evolves over successive generations toward an optimal solution. The solution process of GA follows different principles as compared with conventional approaches. These fundamental differences are as follows: - GA uses objective function. - Instead of using a single point, it uses a population of design points or variables that avoid a local optimum solution. - Strings of binary numbers represent the design variables, which are similar to chromosomes in genetics, so discrete and integer problems are naturally applicable to GA. GA avoids falling into local optimums by sustaining multiple points to multiple-point approaches of each generation. In such a method, the probability of surviving the best, fittest solution is high as compared with a low-fitness solution. As a result, the GA mostly will result in a global optimal solution. GA techniques consists of five basic phases: - Initial population - Fitness function - Selection - Crossover - Mutation The process begins with an initial population comprising a set of individuals (i.e., solutions) within a search space. An individual is characterized by a range of combinations of the design variables (or parameters) termed “genes,” which are joined into a string to form a chromosome (or solution). For each solution, the objective function is assessed with regard to its level of fitness. Each solution is paired with another to form a mating pair, used for reproduction of subsequent populations. The mating pairs produce new solutions as offspring, which retain values of the design variables generated by crossover of the parents’ values. In addition, random mutation is introduced to some of the new solution’s values. The process of GA technique is random, even though its optimization permits one solution to establish the level of control.

Analysis of Crude Oil Production Using Gas Lift

Gas lift is used to increase production by reduction in the density of the oil column in the tubing, reduction of the flowing bottom-hole pressure which is affected by the hydrostatic pressure of the fluid column and by providing external energy to the oil. In this study an oil field in the Niger Delta was used as case study; it has a production life span of over ten years with characteristics such as high gas-oil ratio (GOR) and high reservoir pressure which makes gas lift suitable for optimizing the wells. The aim of this study is to select the gas lift method suitable for optimum production in the wells using the production modelling softwares PROSPER, and GAP. Simulation studies were conducted using data from two wells in the oil field. The performance of continuous and intermittent gas lifted performance on two wells were compared. The results indicated that continuous gas lift system will be suitable for a well that has high flow rate and high GOR. Also, intermittent gas lift system will be suitable for a well that has lower reservoir pressure and low productivity. Sensitivity analysis of water cuts, gas injection rates and well head pressures were carried out to investigate how the wells will respond to changing operating conditions such as increasing water cut, increasing gas injection rates and increasing well head pressures in the future.

To Design a Continuous Gas Lift Method for Improving Production in a Dead Well: A Case Study

In Petroleum industry the goal of production department is to obtain maximum oil production at minimum expenditures. The oil production from the wells decreases after some period due to decline in reservoir pressure, increase in water cut, water conning etc. in other words the revenue is lost. Therefore, the artificial lift system is installed on the wells depending upon its characteristics. Gas lift system is one of the most popular artificial lift systems to optimize oil recovery employed in petroleum industry. In gas lift system, gas injected into the well through gas lift valves which reduces the density of liquid column in the well which in turn causes the oil to be produced at the surface. This research study is conducted on well named A-1 in an onshore field Alpha, the well is considered dead due to increase in water cut (40%). The objectives of this research study are to unload the well by designing an efficient continuous gas lift method and then optimize the production by varying some parameters. For this purpose, a simulation model of base case well and gas lift case is designed on PROSPER software by entering the PVT properties, well properties and reservoir properties. After that a sensitivity analysis is performed on PROSPER by changing some variables such as; water cut, wellhead pressure, skin factor, gas injection rate and casing pressure. Subsequently designing the model of the well with gas lift method the well started to produce oil at suitable rate. After that the production is optimized by performing sensitivity analysis on some variables and optimum oil production rate vs gas injection rate is obtained.

Influence of wellhead pressure and water cut in the optimization of oil production from gas lifted wells

The worldwide increase in energy demand necessitates the development and optimization of marginal oil fields for sustenance. In this regard, effective and economic production of fluids are heavily relied upon the artificial lift techniques as the reservoir's natural energy may not be able to deliver the fluids to the surface. Gas lift is a widely practised and successful method that is suitable for rejuvenating the oil production from such fields. In this study, the influence of critical parameters like water cut, wellhead pressure (WHP) and gas-lift gas injection rate on the output from a gas lifted well was analysed. A significant reduction in the oil production was observed with the increase in water cut. For a fixed gas injection rate of 1 Mmscf/day, the production decreased by 26.90% when the water cut increased from 15% to 30% and further by 50.80% when the water cut reached 45%. An increase in the gas injection rate from 1 Mmscf/day to 8 Mmscf/day resulted in an increase in the production rate by 29.21%, 40.48% and 56.56% for 15%, 30%, and 45% water cut conditions, respectively. It was observed that there is a drop in the oil rate with the increase in WHP for a constant gas injection rate. An increase in the WHP from 100 psi to 300 psi resulted in a drop in the oil production rate by 11.01%, 11.78% and 12.74% for 15%, 30% and 45% water cut conditions, respectively. The study sheds light on the significance of optimizing the critical parameters to maximize the production from a well, with severely affected productivity, using a continuous gas lift system.

A Robust Short-Term Oil Production under a Bow-Tie Uncertainty Set for the Gas Lift Performance Curve

SummaryThe method of continuous gas lift has been commonly used in the oil industry to enhance production. Existing optimization models consider an approximate performance curve anchored by production test data, often disregarding reservoir uncertainty. We propose a robust optimization model that jointly considers the most recent data and an uncertainty set for the reservoir pressure, a critical parameter that is usually not measured precisely. As a result, we obtain what we call a “bow-tie” uncertainty set for the performance curves, in which the performance uncertainty increases when we move away from the production test’s operational point. We test our model with real data from an offshore oil platform and compare it against a fully deterministic model. We show superior out-of-sample performance for the robust model under different probability distributions of the reservoir pressure.

Short-term oil production global optimization with operational constraints: A comparative study of nonlinear and piecewise linear formulations

The short-term oil production optimization of offshore platforms which use continuous gas lift and consider several operational constraints is a challenging task, specially when decision variables include both continuous and integer ones. The intrinsic non-linearity of the Gas Lift Performance Curves (GLPC) naturally yields to Mixer-Integer Nonlinear Program formulation. Picewise linear approximations of the GLPC are usually applied in order to reduce the complexity of the optimization problem and to ensure an approximate solution, leading to Mixer-Integer Linear Program formulation. However, a comprehensive and comparative study of these two formulations for the oil production optimization problem is scarce in the literature. This paper provides a deep performance evaluation of these two approaches, showing the limitations of both strategies, and proposes a hybrid two-stage optimization strategy to achieve the global optimal operating condition which maximizes the oil production subject to safety, environmental and processing capacity constraints.

Optimisation of Artificial Lifts Using Prosper Nodal Analysis for BARBRA-1 Well in Niger Delta

Hydrocarbon exploration basically requires effective drilling and efficient overpowering of frictional and viscosity forces. Normally, frictional power losses occur in deep well systems and it is essential to analyse each component of any well system to determine where exactly pressure is lost, and this can be done using Nodal Analysis. In this study, nodal analysis has been carried out with the use of PROSPER, a software for well performance, design and optimisation. Artificial lifts can then be used to solve the problem of frictional power losses. To increase the production of Barbra 1 well in the Niger Delta and hence extend its functional life, we have applied nodal analysis. Modelling results for three artificial lift methods; continuous gas lift, intermittent gas lift and electrical submersible pump were found to be 1734.93 bbl/day, 451.50 bbl/day and 2869 bbl/day respectively. The output from the well performance without artificial lift was 1370.99 bbl/day by applying Darcy’s model. Meanwhile, the output from the well without artificial lift is 89.90 bbl/day when aided with productivity index (PI) entry, the normal model for intermittent gas lift. Hence, from the comparative analysis of the results obtained from this study, it was deduced that when artificial lifts are employed, the well output increases significantly from 1370.99bbl/day to 2869 bbl/day (electrical submersible pump). This study concludes that wells such as Barbra 1 are good candidates for artificial lift, and this is evidenced by increasing productivity.
 Keywords: Production optimisation, nodal analysis, prosper simulator and barbra well.

GAS LIFT OPTIMIZATION OF A MATURE WELL IN NIGER DELTA, NIGERIA USING INCOMPLETE DATASET: A CASE STUDY

Well DEF, a well located in Niger Delta region of Nigeria was shut down for 7 years. On gearing towards re-starting production, different options such as installation of gas lift mechanism, servicing and installation of packers and valves were evaluated for possibility of increasing well fluid productivity. Hence, this research was focused on optimizing well fluid productivity using PROSPER through installation of continuous gas lift mechanism on an existing well using incomplete dataset; in addition, the work evaluated effect of gas injection rates, wellhead pressure, water cut and gas gravity on efficiency of the artificial lift mechanism for improved well fluid production. Results of the study showed that optimum gas injection rate of 0.6122 MMscf/day produced well fluid production of 264.28 STB/day which is lower than pristine production rate (266 STB/day) of the well. Also, increment in wellhead pressure resulted in decrease in well production, increase in water cut facilitated reduction in well fluid productivity while gas gravity is inversely proportional to well fluid productivity. Based on results obtained, authors concluded that Well DEF does not require gaslift mechanism hence, valves and parkers need to be re-serviced and re-installed for sustained well fluid.

Application of Artificial Intelligence to Estimate Oil Flow Rate in Gas-Lift Wells

Optimization and monitoring schemes for oil well and reservoir system require accurate estimation of production rate. Real-time monitoring is conducted typically using flow transmitters that contain their own inherent uncertainties due to flow of multiple fluids. Because of these limitations, industrial practices involve the usage of wellhead conditions and intermittent well test data to estimate well flow rates through certain established correlations such as Gilbert’s empirical model. These correlations, however, have become ineffective due to inadequate well test data and associated operational and cost-intensive commitments. The main objective of this work was to utilize artificial intelligence (AI) techniques to develop robust correlation to predict oil rates in gas-lift wells. The AI techniques implemented in this study are artificial neural network (ANN), artificial neuro-fuzzy inference systems, support vector machines, and functional networks. In addition, ANN was used to develop physical equation to predict oil flow rate. Separator test dataset from multiple wells of an oil field operating on continuous gas lift was collected. Extensive data analytics were performed before feeding it in the algorithms. The inputs consisted of only the easily available surface parameters. All the developed AI models were compared among themselves as well as with conventionally used empirical models. The comparison was conducted based on average absolute error percentage and coefficient of determination. The newly developed AI model can predict oil rates with accuracy exceeding 98% that is extremely efficient, and examples of such results have not been reported previously.