Application Of Horizontal Wells Research Articles

Application of Seagull Optimization Algorithm-BP Neural Network in Oil-Water Two-Phase Flow Pattern Forecasting

With the ongoing increase in global energy demand, the significance of innovations in oil exploration and development technologies is rising, especially in relation to the development of unconventional reservoirs. The application of horizontal wells is becoming increasingly important in this particular situation. However, accurately monitoring and analyzing fluids in horizontal wells remains challenging due to the complex and fluctuating flow patterns of oil-water two-phase flow within the wellbore. Several elements, including well slope angle, flow rate, and water content, are involved. This study aimed to explore and develop an effective method for forecasting flow patterns, improving the precision of the dynamic monitoring of oil-water two-phase flow in horizontal wells. By analyzing the flow patterns in different experimental conditions, a predictive model using the SOA-BP neural network was developed, providing a scientific basis for dynamic monitoring in actual production scenarios. Initially, the simulated experiment for oil-water two-phase flow was carried out at room temperature and pressure utilizing a multiphase flow simulator. An optically transparent wellbore, with a diameter comparable to that of a real downhole well, was utilized, and No. 10 industrial white oil and tap water were employed as the experimental fluids. The experiment considered multiple contributing factors, including different well deviation, total flow, and water cut. The flow characteristics of oil and water were observed via visual monitoring and high-definition video, followed by detailed analysis. After collecting the experimental data, flow regimes for various scenarios were classified based on the established theory of oil-water two-phase flow in horizontal wells; then, detailed flow distribution diagrams were drawn. These data and diagrams presented offer a visual representation of the behavioral patterns exhibited by oil-water two-phase flow under varying situations and form the basis for subsequent model training and testing. Subsequently, based on the experimental data, this study combined the Seagull Optimization Algorithm (SOA) with a BP neural network to effectively learn and predict the experimental data. The SOA optimized the weights and biases of the BP neural network, improving the model’s convergence speed and prediction accuracy. Through rigorous training and testing, an oil-water two-phase flow pattern forecasting model was established, effectively predicting flow patterns under different well deviation, total flow, and water cut conditions. Finally, to validate the efficiency of the established model, a total of 15 data points were chosen from a sample well for validation. By comparing the flow patterns predicted by the model with actual logging data, the results indicate that the model’s accuracy in identifying flow pattern was 86.67%. This demonstrates that the flow pattern prediction model based on the SOA-BP neural network achieved a high level of accuracy under different complicated working conditions. This model effectively fulfills the requirements for dynamic monitoring in actual production. This indicates that the SOA-BP neural network-based flow pattern forecasting method is highly valuable due to its practical application value and provides an efficient technical approach for the development of unconventional reservoirs and the dynamic monitoring of horizontal wells in the future.

Uniform Acid Cleaning Technology and Its Application in Horizontal Wells with Open Hole Screen Tube

After the completion of the open hole sieve tube in a horizontal well, it is necessary to replace the slurry and put it into production. Generally, circulating acid outside the tube cannot fully remove mud pollution. The acidification process needs to fully consider the heel effect of horizontal wells. Based on the horizontal pipe flow model and the characteristics of foam diversion, a mathematical model of acid washing suitable for open hole screen horizontal wells is established. Analysis suggests that lower flow rates and higher fluid viscosity during the acid washing process are more conducive to the uniform entry of the plugging solution into the formation. We have designed a uniform liquid mixing equipment with a flow blocking mechanism, and improved the acid washing construction process to achieve negative pressure reverse discharge of acid solution. This process can achieve uniform entry of the unblocking fluid into the formation after passing through the screen gap, and remove the blockage of the mud layer inside and outside the near screen tube. The horizontal wells using this process have a 30% increase in production capacity compared to oil wells in the same block, and the high yield validity period has been extended by 680 days.

Performance of Horizontal Wells Completed in Unconsolidated Sand: Case Study Niger-Delta

Drilling and completion of horizontal wells have been proven to be a productive and profitable project, in comparison with the performance of the conventional vertical wells. However, in Nigeria there are very few application of horizontal wells as open-hole, this is largely due to the unconsolidated nature of Niger-Delta sands. This study examined the completion of open-hole horizontal wells with a case study of a field which is located within the Niger-Delta region in Nigeria. Two (2) wells which have been successfully drilled and completed were sampled. To achieve this, the performance of the completion option was examined using an analytical approach. This implored the Joshi’s model and Vogel’s equation to construct the Inflow Performance Relationship (IPR) plot. The vertical lift performance (VLP) was considered by employing Gilbert’s method. From the combined plots, the optimum operating condition of the wells indicated that well A has a productivity index of 1.039 Stb/day/psi with a maximum flow rate of 3250 Stb/day, while well B has a productivity index of 1.156 Stb/day/psi and maximum rate of 3370 Stb/day. The results show that horizontal well projects executed in fields within the Niger-Delta region can be expected to produce at good rates as obtained in other regions of the world. With the production capacity shown by these wells, improved conventional ultimate recovery is assured. Keywords: Horizontal Well, Inflow Performance Relationship, Open-hole, Productivity index, and Vertical Lift Performance. DOI: 10.7176/JEES/11-10-07 Publication date: October 31 st 2021

An Improved Study of Emulsion Flooding for Conformance Control in a Heterogeneous 2D Model with Lean Zones

Summary Use of oil-in-water (O/W) emulsion has shown its potential for conformance control in heterogeneous porous media, yet it is essential to understand how to improve the conformance control performance in the heterogeneous 2D model with lean zones before it is applied in the fields. In this paper, an O/W emulsion-based conformance control method is improved through newly designed flow tests and optimized modeling study. A heterogeneous 2D model was designed with a high water mobility zone (HWMZ) and a low water mobility zone (LWMZ) separated by a horizontal injection well to mimic real oil sands with lean zones (top- or bottomwater) and with application of horizontal wells. Optimal conformance control strategies were proposed and examined in the 2D model by injecting correspondingly designed O/W emulsions. In an improvement of our previously proposed emulsion flow model (Ding et al. 2020c), we introduce the real phenomena of permeability reduction (PR) coefficients in this paper to describe the three ambiguous coefficients: flow distribution coefficient (γ), plugging coefficient (α), and retention rate coefficient (a). This newly developed model can incorporate with characteristics of the emulsion and the heterogeneous porous media through the introduction of the experimentally derived PR coefficient. It is well established in COMSOL Multiphysics® (COMSOL AB 2005), and the modeling results show good agreement with the experimentally monitored results in the three types of flow tests. This work bridges experimental and mathematical studies on emulsion flow in 2D models associated with lean zones and is able to provide a guide on optimal emulsion design and injection strategy for optimal conformance control performances.

Horizontal Wells: Applications, Considerations, and Case Histories

This paper discusses many aspects of the application of horizontal wells for field development, starting with the basic question of why to opt to this technology. The different considerations to be taken into account when dealing with the technology are reviewed, including some inherent downsides like higher cost and operational complications. The main emphasis, however, is placed on practical reservoir engineering aspects, including well planning and performance, and the handling of horizontal wells in specific technical applications like well test
 analysis and numerical modeling.
 
 
 
 The theoretical basis and pertinent differences in physics and flow regimes around vertical and
 horizontal wells are discussed in the context, together with the inherent practical implications.
 Case histories and examples are presented for several successful applications worldwide that the author was involved in. In one case, a medium size field offshore Canada was developed with waterflood utilizing very few horizontal producers, with a set of horizontal and vertical water injectors. Detailed planning and intensive modeling, carried out by a team of engineers and geoscientists, led to a remarkably
 successful field development. In another case, few horizontals were used among many directional wells to develop a Mediterranean oil reservoir under aquifer and gas cap drives in an attempt to reduce coning problems, raising an opportunity to compare the long term performance of different geometry wells.
 A brief description is also presented to some advanced techniques and special cases of implementing horizontal wells such as thermal recovery (Steam-Assisted-Gravity-Drainage, or SAGD Process), multi-lateral wells, and multi-fractured wells, with discussion on these applications. Under favorable conditions, horizontal wells can also be used as an Improved Oil Recovery (IOR) tool in mature fields, an application that became very common in many super giant fields in the Arabian Gulf Area.

SUCCESSFUL APPLICATION AND LIMITATIONS OF HORIZONTAL WELLS

In fields with low-permeable reservoirs, the use of vertical wells becomes economically unprofitable, since a significant amount of reserves remains not involved in development. In these conditions, the most rational use of horizontal wells becomes.
 A horizontal well is drilled parallel to the plane of the reservoir and can drain a larger area than a vertical one, which makes it possible to increase the impact of the working agent. This, in turn, leads to an increase in well productivity and, ultimately, to an increase in oil recovery of productive formations.
 Due to the horizontal wellbore, fractured areas are exposed, due to which the flow rates of these wells increase somewhat compared to vertical ones. It becomes possible to develop a reservoir with minimal drawdowns with a much smaller number of wells.
 The purpose of this article is to provide a brief overview of the field application of horizontal wells in various reservoir conditions. The review of economically successful and unsuccessful wells allows the creation of a certain kind of list of parameters that are of the greatest importance for consideration in order to select a commercially successful application of horizontal wells.

Characterising the application of horizontal wells and indirect hydraulic fracturing for improved coal seam gas drainage

Historically, horizontal wells in coal seam gas (CSG) producing areas of Australia have been limited in their ability to stimulate horizontal wellbores with hydraulic fractures, despite most basins being in favourable stress states capable of generating multiple transverse hydraulic fractures. In some cases, overlapping mining tenements limit the ability to effectively deploy steel casing completions to effectively manage multi-stage fracture stimulations along the lateral. In other cases, potential wellbore instabilities preclude the placement of laterals with adequate length to stage numerous fractures required to make a well economic. Strike Energy’s Jaws 1 well indicated well instability when drilling horizontally in the Patchawarra Vu Coal Seam in Petroleum Exploration Licence 96 of the Weena Trough in the Cooper Basin. To overcome this instability, Strike Energy introduced the application of an innovative process of deploying multiple, indirect hydraulic fractures in Jaws 1ST from a horizontal wellbore underlying the coal. Microseismic and surface deformation tiltmeter data acquired during the treatment confirmed the successful placement of fractures in the Patchawarra Vu Coal Seam. Further, chemical tracing and production testing provide further insight into the placement and effectiveness of the overall stimulation. Through analyses of data from the Jaws 1ST, we provide insight and recommendations regarding horizontal well placement to improve indirect hydraulic fracture effectiveness. These recommendations would be applicable for other Australian CSG basins where direct horizontal well drilling and fracture stimulation has been limited (e.g. overlapping mining tenements) or where horizontal well instabilities limit drilling within the seam (i.e. Cooper Basin, depleted coals).

Design and Implementation of the Array Logging Tool on Horizontal Production Logging

The measuring instruments have some errors in the measurement of high water cut production wells, and many domestic oil fields are also in high water cut state. The measured data from the conventional production logging instrument are all almost inaccurate. This project has designed a staggered probe array flow meter well logging apparatus based on the characteristic of electromagnetic wave specific retention meter that can fully cover the wellbore fluid and improve flow measurement accuracy. According to the application in horizontal wells, the accuracy of this measuring instrument now has been proved to be more than 90% and can meet the requirements of production logging interpretation in horizontal wells.

A Review of Gas Flow and Its Mathematical Models in Shale Gas Reservoirs

The application of horizontal wells with multistage hydraulic fracturing technologies has made the development of shale gas reservoirs become a worldwide economical hotspot in recent years. The gas transport mechanisms in shale gas reservoirs are complicated, due to the multiple types of pores with complex pore structure and special process of gas accumulation and transport. Although there have been many attempts to come up with a suitable and practical mathematical model to characterize the shale gas flow process, no unified model has yet been accepted by academia. In this paper, a comprehensive literature review on the mathematical models developed in recent years for describing gas flow in shale gas reservoirs is summarized. Five models incorporating different transport mechanisms are reviewed, including gas viscous flow in natural fractures or macropores, gas ad-desorption on shale organic, gas slippage, diffusion (Knudsen diffusion, Fick diffusion, and surface diffusion), stress dependence, real gas effect, and adsorption layer effect in the nanoshale matrix system, which is quite different from conventional gas reservoir. This review is very helpful to understand the complex gas flow behaviors in shale gas reservoirs and guide the efficient development of shale gas. In addition to the model description, we depicted the type curves of fractured horizontal well with different seepage models. From the review, it can be found that there is some misunderstanding about the essence of Knudsen/Fick diffusion and slippage, which makes different scholars adopt different weighting methods to consider them. Besides, the contribution of each mechanism on the transport mechanisms is still controversial, which needs further in-depth study in the future.

Application of horizontal wells in three-dimensional shale reservoir modeling: A case study of Longmaxi–Wufeng shale in Fuling gas field, Sichuan Basin: Reply

Three-dimensional reservoir modeling is an important aspect to determine the heterogeneity of organic-rich shale reservoirs, an area of study that continues to be explored and refined. A large proportion of data acquired from horizontal wells causes issues in the structural and property modeling for shale reservoirs. Since horizontal wells are designed to drill into a specific, narrow zone, their horizontal section tends to parallel or nearly parallel formation surfaces. As a result, formation surfaces have a much more complex spatial location relationship with horizontal wellbores than with vertical wellbores. The existing algorithms are not good at addressing this issue during structural modeling. The major problem of using horizontal well data in property modeling is the biased data set because their horizontal section tends to stay within a narrow zone. The property distribution feature estimated from this biased data set, as a significant, default input of geostatistical simulation algorithms, causes the constructed property models to deviate away from the real case in the subsurface. A method to infer more formation tops in pseudovertical wells according to a series of assumptions was developed to provide more constraint points for structural modeling within the areas of the horizontal well section. To use the biased database from horizontal wells, distribution function and trend model methods were developed for continuous property modeling, and percentage and probability trend models were developed for discrete property modeling. The Longmaxi–Wufeng shale in the Fuling gas field of Sichuan Basin was used as an example to express and verify these methods.

Application of horizontal wells in three-dimensional shale reservoir modeling: A case study of Longmaxi–Wufeng shale in Fuling gas field, Sichuan Basin: Discussion

Application of horizontal wells in three-dimensional shale reservoir modeling: A case study of Longmaxi–Wufeng shale in Fuling gas field, Sichuan Basin: Discussion

Study of mud weight window of horizontal wells drilled into offshore natural gas hydrate sediments

Drilling horizontal wells into natural gas hydrate (NGH) sediments may be one of the most promising methods to increase the cost effectiveness of the exploration of NGH. However, many challenges, such as wellbore collapse and wellbore fracturing, will be encountered. Therefore, an accurate prediction of the mud weight window (MWW) is very important. In this work, a model was built to calculate the MWW of horizontal wells drilled into offshore NGH sediments, considering the NGH saturation and the effects of inlet parameters of the drilling mud, and was combined with the transient heat transfer model to calculate the temperature distribution of the borehole. A case study was carried out, and the effects of several parameters were discussed: 1) When drilling horizontal wells in NGH sediments, the dissociation of NGH in the formation will not occur. 2) With increasing circulation time, the borehole will be cooled, and the cooling effect will lead to a decrease in both the fracture pressure and collapse pressure of the target zone. 3) The mud flow rate has a large influence on the mud temperature profile, especially in the horizontal section, and a higher mud flow rate leads to a lower fracture pressure and collapse pressure in the target zone. 4) The inlet temperature has limited influences on the mud temperature profile in the horizontal section and the MWW of the target zone. 5) The saturation of NGH in a formation has a significant influence on the collapse pressure but little influence on the fracture pressure, and higher saturation will lead to a wider MWW. This study will support the safe control of well stability and application of horizontal wells drilled into offshore NGH sediments.

Application of horizontal wells for cyclic steam stimulation (CSS) in bitumen recovery: production optimization through reservoir simulation

By declining conventional oil resources, global attention has turned to unconventional ones. Nonetheless, the heavy and viscous nature of bitumen prevents its flow at reservoir condition, which has paved the way for the progressive development of in situ thermal methods to lower the viscosity of bitumen and increase its mobility. Cyclic steam stimulation (CSS) is an alternative method to recover bitumen at higher depths. Using CSS in conjunction with horizontal wells extends the advantages of this method by increasing sweep efficiency, contact area opened to flow, and steam injectivity. In this study, the performance of CSS in the Athabasca region during 10 years was studied and sensitivity analysis of operational parameters was carried out. The effect of various factors was investigated to find the optimum case. The model under study is a sector of Athabasca bitumen deposit which was simulated by CMG-STARS (version 2006.1). Black oil model was used to simulate the behavior of bitumen in porous media. The studied bitumen consists of 91.5% asphaltene and 8.5% maltene. Its viscosity during 10 years of production changed from 755.5 cp to 16.8 cp representing the viscosity reduction as a dominant mechanism of bitumen production. The maximum bitumen recovery factor in the base case was found to be 4.3%. In addition, optimum soaking time was determined to be 20 days.

Efficiency of Inhibitive Mud Application in Horizontal Wells

Currently, we have been witnessing the increasing number of problems in drilling caused by certain challenges in drilling through depleted reservoirs, complicated geological settings, and fast-growing technology of extended reach drilling. One of the methods used to solve the problems is casing-while-drilling. The authors have been studying the difficulties occurring while using this method with a special focus on the issue of torque increase while rotating a casing string at an excessive speed. The paper presents calculations of the torque taking into account the friction coefficient. As an effective solution to reduce the torque a new centralizer has been designed in the laboratory of the Department of Oil and Gas Well Drilling of Almetyevsk State Oil Institute. While performing casing drilling operations a new centralizer with roller balls attached makes it possible for rolling friction to be replaced with sliding friction and, thus, prevent thread stripping.

The mechanism of drainage gas recovery and structure optimization of an internal vortex tool in a horizontal well

Effective drainage gas recovery technology is the key to solving the problem of the liquid loading of gas well and of enhanced gas recovery. An internal vortex tool is designed for solving the problem of liquid loading in horizontal wells. This study conducted a computational fluid dynamics analysis the efficiency of the drainage gas recovery of the tool in the horizontal well, to optimize the structure of the tool. The results show that most of the liquid film flows along the pipe wall in the internal vortex tool, and the gas flows through the central area of the pipe at a high speed with fog. The internal vortex tool can increase the gas phase velocity and separate the gas and liquid. The structural parameters of the internal vortex tool for minimum pressure loss and the maximum drainage efficiency is the same diameter as the tubing and casing for the runner diameter, 42.8° for the swirl angle, 8 mm for the helix height, 6 mm for helix width and 4 for the number of lead. The study on the flowing of a gas liquid swirling flow in the internal vortex tool proves the feasibility of its application in horizontal wells. It can provide theoretical guidance and a practical basis for efficient liquid loading using the internal vortex tool in the future.

Application of horizontal wells to the oceanic methane hydrate production in the Nankai Trough, Japan

Due to the complicated reservoir conditions in the oceanic methane hydrate (MH) reservoir in the Nankai Trough, Japan, the gas production rate for the economical extraction had not been achieved during the current field production tests in 2013 and 2017 using vertical wells. Therefore, this study aimed at the application of the horizontal wells to the oceanic MH production in the Nankai Trough. Since there existed three sub-hydrate-bearing layers with different physical properties (i.e., initial hydrate saturation, porosity, and intrinsic permeability) in the reservoir, some possible well configurations including single horizontal well patterns and dual horizontal well patterns were designed based on a multilayered geological model simulating the real oceanic MH reservoir in the Nankai Trough. Then, the effectiveness of these two kinds of well designs was verified via long-term simulations of the oceanic MH production by simple depressurization, and the optimal well configuration for each design was recommended. Furthermore, a combined method of depressurization and hot water injection was also tested based on the dual horizontal well pattern, and the sensitivity analyses indicated that a favorable gas production rate of 8.64 × 105 m3/day could be obtained within the first year, even under a relatively low injection temperature of 40 °C and a relatively small injection rate of 2 kg/s/m of well.

Application of horizontal wells in three-dimensional shale reservoir modeling: A case study of Longmaxi–Wufeng shale in Fuling gas field, Sichuan Basin

3-D reservoir modeling is an important aspect to determine the heterogeneity of organic-rich shale reservoirs, an area of study that continues to be explored and refined. A large proportion of data acquired from horizontal wells causes issues in the structural and property modeling for shale reservoirs. Since horizontal wells are designed to drill into a specific, narrow zone, their horizontal section tends to parallel or nearly parallel formation surfaces. As a result, formation surfaces have a much more complex spatial location relationship with horizontal wellbores than with vertical wellbores. The existing algorithms are not good at addressing this issue during structural modeling. The major problem of using horizontal well data in property modeling is the biased dataset as their horizontal section tends to stay within a narrow zone. The property distribution feature estimated from this biased dataset, as a significant, default input of geostatistical simulation algorithms, causes the constructed property models to deviate away from the real case in the subsurface. A method to infer more formation tops in pseudo vertical wells according to a series of assumptions was developed to provide more constraint points for structural modeling within the areas of the horizontal well section. To use the biased database from horizontal wells, distribution function and trend model methods were developed for continuous property modeling, and a percentage and probability trend models were developed for discrete property modeling. The Longmaxi-Wufeng shale in the Fuling gas field of Sichuan Basin was used as an example to express and verify these methods.

Description and Regulation of Drilling Completion Fluid Cake Structure

In the process of oil and gas well drilling and completion, under the action of positive pressure gradient or self-absorption, drilling and completion fluid solid phase particles block the reservoir pore and form the filter cake. The filter cake plays a vital role in reservoir protection, and is closely related to the oil and gas well productivity from cake formation to remove. The filter cake is always expected to be thin, tough, with low permeability and easy to remove. Many scholars made a lot of research from the filter cake layer structure, space truss structure, pore structure and the structure of fractal structure of filter cake. However, the researches on the structure of the filter cake are mainly conducted qualitatively at home and abroad, while the quantitative research progress is slow. At the same time, the research on the relationship between the filter cake structure and its performance is also relatively weak. In recent years, with the wide application of horizontal wells, it has called widespread attention on how to effectively remove filter cake in order to improve the oil and gas well production capacity at home and abroad. The widely-used filter cake removal technology mainly includes natural clear, mechanical removal, chemical removal and biological removal technology currently. Among them, the biological removal technology is developed in recent years as a new type of filter cake removal technology. With the further development of mud cake removal technology and downhole filter cake removing circumstance with increasing complexity, a single filter cake removal technology cannot completely meet the requirements. The filter cake removal technology is developing in the direction of the composite to clear, in order to obtain ideal filter cake removal effect.

Применение горизонтальных скважин для повышения эффективности освоения и ускорения ввода в эксплуатацию морских месторождений Северного Каспия

Применение горизонтальных скважин для повышения эффективности освоения и ускорения ввода в эксплуатацию морских месторождений Северного Каспия

Oriented cluster perforating technology and its application in horizontal wells

An oriented cluster perforating technology, which integrates both advantages of cluster and oriented perforating, will help solve a series of technical complexities in horizontal well drilling. For realizing its better application in oil and gas development, a series of technologies were developed including perforator self-weight eccentricity, matching of the electronic selective module codes with the surface program control, axial centralized contact signal transmission, and post-perforation intercluster sealing insulation. In this way, the following functions could be realized, such as cable-transmission horizontal well perforator self-weight orientation, dynamic signal transmission, reliable addressing & selective perforation and post-perforation intercluster sealing. The combined perforation and bridge plug or the multi-cluster perforation can be fulfilled in one trip of perforation string. As a result, the horizontal-well oriented cluster perforating technology based on cable conveying was developed. This technology was successfully applied in unconventional gas reservoir exploitation, such as shale gas and coalbed methane, with accurate orientation, reliable selective perforation and satisfactory inter-cluster sealing. The horizontal-well oriented cluster perforating technology benefits the orientation of horizontal well drilling with a definite target and direction, which provides a powerful support for the subsequent reservoir stimulation. It also promotes the fracturing fluid to sweep the principal pay zones to the maximum extent. Moreover, it is conductive to the formation of complex fracture networks in the reservoirs, making quality and efficient development of unconventional gas reservoirs possible.