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Increased production alongside low costs has always been a long-standing goal for operators in a time where the industry is thriving to increase their operational and economical efficiencies. For maturing fields, operators are constantly seeking innovative techniques to access large quantities of reserves found in low permeability formations.
The nature of the reservoir has resulted in an economical need to implement a hydraulic fracturing campaign. This would assist with increased production through wider contact area of the producing interval. After a campaign resulting in favorable results through hydraulic fracturing, additional efficiencies addressing the operational and cost concerns of cemented plug & perf were required. In order to maintain production increases while maintaining operational efficiency, the need for multi-stage hydraulic fracturing became evident.
Six candidate wells were selected for proppant fracturing utilizing a multi-stage completion technique that has been widely adopted in North America for the past 17 years and internationally for over a decade. The technique utilizes a series of hydraulic mechanical packers and fracturing ports that are shifted open sequentially across the applicable zones targeted for treatment. The ports have seats that are sized to respective balls, which are used to isolate the stimulated intervals. The system allows for increased efficiency through eliminating the risks associated with wireline operations for perforating, or coiled tubing operations to mill out bridge plugs. It also allows for immediate and simultaneous production from all stages as well as contingencies for shutting off water zones. From June 2016 to March 2017, six systems were installed consisting of 6 to 8 hydraulic fracturing stages, which were placed in cased-hole pre-perforated wells.
This paper investigates reservoir quality assessment as well as the stimulation efficiency and productivity enhancement of the Sidri Field. It investigates two different completion methodologies to investigate operational efficiency and productivity enhancement of the Sidri Field in the Sinai Peninsula. The comprehensive evaluation will involve discussions of candidate selection, pre-job design alongside comparisons of timeline, cost, zonal isolation, and productivity to help serve as a guideline for operators in the region looking to enhance their completion approach.
Rock brittleness and total organic carbon (TOC) are two essential parameters that are needed to evaluate unconventional reservoirs. Brittleness is a crucial rock physics property that is used to guide both completion and hydraulic-fracturing designs.
The brittle shale is more likely to be naturally fractured and more likely to respond well to hydraulic fracturing. Ductile shale, on the contrary, is more plastic, absorbs energy, and is not considered neither a good producer nor a desirable hydraulic-fracturing interval. In such cases, formation tends to heal any natural or induced fractures. Thus, intervals with high brittleness are considered a good candidate for hydraulic fracturing. However, many authors argue that this viewpoint is not reasonable because rock brittleness is not an indicator of rock strength and the current brittleness indices are based on elastic modulus or mineralogy. Brittle rock just has shorter plastic deformation, and it is not certain that it is easier to fracture brittle rock than ductile rock since brittle formation may have greater strength than ductile formation.
TOC is the measure of the total of carbon present in an organic compound and is usually used as an important factor for unconventional shale resources evaluation. In this study, we show an application of estimating total organic carbon (TOC) in a Khataba play from the triple combo logs using curve fitting. This paper also presents a brittleness model that uses the triple combo log. Logging and laboratory core testing data were collected from Khataba shale wells in Egypt. Laboratory testing was conducted to understand the complex rock mineralogical composition. Geomechanical rock properties derived from analysis of full-wave sonic logs and core samples were combined to develop sophisticated models to verify the principle of brittleness and fracability indices and to demonstrate the process of screening hydraulic-fracturing candidates. Tensile and compressive strength tests are conducted to understand rock strength better. Once the data were available, different methods were used to calculate brittleness index considering the effect of mineralogical composition and elastic moduli.
Most of the Egypt's Western Desert plays are characterized as tight reservoirs. In early development stages, only the high permeability layers called “conventional reservoirs” were produced. The unconventional, challenging layers were not considered economical because of the high stimulation costs. As the high-permeability layers became more mature and showed a sharp decline in production, the tight layers/zones were targeted by operators to unlock the enormous amount of hydrocarbons and to achieve the economical production targets from these marginal fields. The government has launched a number of studies to evaluate, explore, and appraise several prospects of unconventional reservoirs. Gas shales were characterized within the Khatatba source rock in the Shoushan basin and a tight carbonate reservoir was observed in the Abu Gharadig basin. A total of six vertical and two horizontal exploratory wells were drilled and completed via multistage hydraulic fracturing in the appraisal stage of the program for collecting the required data. The pilot data were used to evaluate the reservoir quality, to demonstrate the availability of reserves, to identify the optimal technology for maximizing productivity, and to set foundations for the future development of these plays.
This paper presents the previous results of field trials and shares some lessons related to the recent appraising and development activities of unconventional plays in Egypt. The properties of these unconventional resources have been reviewed to unlock their potential. In addition, the best strategies of field development were highlighted to capitalize the promising potential from these reservoirs through an advanced workflow. This study sheds light on the recent unconventional gas appraisal and development activities. The results indicate that Egypt holds substantial resources of unconventional gas that can play a key role in positively changing the country's production.
Developing unconventional resources and unlocking the enormous amounts of hydrocarbons are gaining more interest. Achieving economical production targets is of key importance, particularly because of the increase in Egypt's domestic demand for energy and production's annual decline from the more mature, high permeability layers. Also, the enormous success in North America's production brought unconventional resources to the forefront of discussion on the future of energy. Five vertical and two horizontal exploratory wells have been drilled and completed via multistage hydraulic fracturing in the Apollonia tight carbonate. Another vertical exploratory well has been drilled and completed in the Middle Jurassic Khatatba source rock with one-stage hydraulic fracturing. Then the well has been flowed back. The goal of this appraisal program was to collect the required data and to set the foundation for the future development of these plays. Laboratory core testing was conducted to understand the complex mineralogy, reservoir characterization, and variable rock fabric. Geological and geochemical studies were conducted to identify the lithostratigraphic section of the Khatatba source rock and to measure the total organic content (TOC), the Rock Eval pyrolosis, and the thermal maturity of hydrocarbon and gas content. Geomechanical rock properties, derived from the advanced petrophysical analysis of newly acquired high-definition triple combo, full-wave sonic logs and core samples testing, were used to determine the rock elastic properties (the Young's modulus and the Poisson's ratio), brittleness and fracturability, and the natural fractures existence (Salah et al., 2016a). Understanding of all of these characteristics helped in reducing uncertainty during hydraulic fracturing operations. Moreover, a stimulation model, which integrated petrophysical and geomechanical data, was built. This paper reviews the findings of the recent activities within unconventional plays in Egypt and summarizes the formation properties, reservoir characteristics, and the flow back analysis of these wells. The lessons learned can form a basis for the subsequent development of various unconventional plays in Egypt.
ElHamid, Ahmed Abd (Qarun Petroleum Company) | Abbas, Mohamed (Qarun Petroleum Company) | Hamed, Eslam (Qarun Petroleum Company) | Ghareeb, Mohamed (Qarun Petroleum Company) | ElSebaee, Mohamed (Schlumberger) | Sweedan, Ahmed (Schlumberger) | Sabet, Ahmed (Schlumberger)
"When everything else fails, frac it" was the sentiment expressed by most engineers who were working on hydraulic fracturing during the late 1970s. This statement indicates how important the hydraulic fracturing technique is, not only in stimulating, and thus greatly increasing, the well's production, but also as a powerful tool to manage the field development. Hydraulic fracturing has become the most applicable and reliable reservoir stimulation technique in all reservoir rock types, even more than the matrix acidizing techniques. Starting from 1940s, when the first hydraulic fracture was performed, until now, the improvement in the hydraulic fracturing technology has never stopped. Currently, the state-of-the-art technology in hydraulic fracturing is the channel fracturing technology or, in other words, open channel fracturing. This is a unique technique of pumping a treatment that helps in forming channels within the proppant pack in the fracture, which improves the fracture conductivity and well productivity.
This study consists of two main parts. The first part is dedicated to the evaluation of the channel fracturing technique by comparing it to conventional fracturing. This comparison depends on three primary evaluation methods. First, well testing data obtained for conventionally fractured wells and wells in which the new technology was implemented were evaluated. Second, the actual production data for offset wells, which were fractured either by conventional technique or by the new channel fracturing one, were analyzed. Finally, an economic comparison of the techniques and an assessment of the gain that can be obtained from the new channel fracturing technique over the conventional one were performed.
After the evaluation and comparison, a statistical analysis was conducted based on a sample consisting of more than 50 wells that were fractured using the channel fracturing technique. This statistical analysis aims to attain the channel fracturing treatment parameters that lead to the best corresponding production results.
These two main parts represents a full evaluation and optimization process that gives a complete picture of the channel fracturing technique and an assessment of the new technique. The assessment considers how to achieve best performance based on a sound statistical analysis constructed by actual day-to-day data and well performance. The assessment proves the economic and production value of the new technique over the conventional fracturing technique, which failed to give the same values.
Recent advancements in technologies pertaining to the drilling of horizontal well and multistage hydraulic fracturing have made it possible to get significant hydrocarbon production even from extremely low permeability formations. Evaluation of the economics is becoming increasingly essential before committing to any big investment. In this scenario, production forecasting plays an important role by not only evaluating the economic feasibility of the project, but also helping in the selection of the most optimal development strategy (
This paper presents an integrated workflow that has been applied in one of unconventional gas bearing formation which is a common reservoir in Egypt’s Western Desert. It does form a reasonable reservoir size and spread over several hundred sq.kms. It is characterized as a low permeability carbonate (0.2 mD) in soft chalk reservoir. Many vertical wells were drilled and completed in the appraisal program for collecting the required data to evaluate reservoir performance before the completion of horizontals, but economical target production rates could not be achieved. To help optimize field development strategy and further increase production, a full field development plan was initiated by drilling horizontal wells with multistage fracturing stimulation. Horizontal pilot wells were drilled and completed along and perpendicular the minimum horizontal in-situ stress direction to enable both transverse and longitudinal fracture propagation patterns for the best completion option.
The objective of this paper is to present an integrated approach to evaluate an unconventional resource, improve the completion efficiency, improving the future fracture design and understand the productivity enhancement specifically in the Western Desert of Egypt, through a detailed analysis of production data and pressure transient analysis.
The conclusions from this study will help in evaluating the behavior of multistage fractured horizontal with different fracture azimuth direction and generate production forecast for different development scenarios. The stimulated rock volume estimation will help in planning the future fracture design to increase well EUR. The proposed workflow and lessons learned formed the basis for subsequent development of various unconventional plays in Egypt.
The ’A’ formation in the Abu Gharadig basin, northern Western Desert of Egypt is a carbonate reservoir characterized as a low-permeability soft chalk with medium porosity and low-quality natural fractures. Owing to these characteristics, achieving economical gas production rates and efficiently developing the reservoir have become increasingly challenging. To increase production from the field, a full development plan was initiated employing drilling of horizontal wells with multistage fracturing stimulation. An integrated and detailed programme of laboratory core testing was conducted to gain an in-depth understanding of this reservoir’s rock mechanics behaviour and to help optimize the hydraulic fracturing and completion designs. Particularly, elastic properties and principal in-situ stresses were acquired to provide the following:
Mechanical properties testing was conducted on selected core samples and integrated logs from two offset vertical wells. The laboratory testing programme consisted of the following:
All laboratory data, including procedures, tabulated results, stress-strain plots, computerized tomography scan images, and post-test sample images are provided for analysis and visualization of the failure mode. Understanding the reservoir geomechanical behaviour and the mechanical parameters that have a critical impact on hydraulic fracturing propagation facilitated improved decision-making in terms of fracturing design and optimization. Hydraulic fracturing simulation software was used to model the propagation of hydraulic fractures based on the integrated reservoir mechanical properties. Different scenarios of perforation clusters were run to model propagation of multiple horizontal fractures and predict the changes in stress anisotropy in the neighbourhood of the fractures .
The Apollonia formation is a tight gas carbonate reservoir characterized as a low permeability soft chalk (Young’s modulus ~ 1 MM psi) with medium porosity and low quality natural fractures. The ability to achieve economical production rates and efficiently develop the Apollonia with those characteristics has become increasingly challenging. To further increase production from the field, a development plan was initiated employing drilling of horizontal wells with multistage fracturing stimulation. An integrated and detailed workflow of laboratory core testing was established to gain an in-depth understanding of this reservoir’s rock mechanics behavior and to help optimize the hydraulic fracturing and completion designs. Particularly, elastic properties and principal in-situ stresses were acquired to provide the following:
The evaluation program of mechanical properties testing was conducted on selected core samples and integrated logs from two offset vertical wells. The laboratory testing program consisted of the following:
All laboratory data, including procedures, tabulated results, stress-strain plots, computerized tomography scan images, and post-test sample images are provided for analysis and visualization of the failure mode. By understanding the reservoir geomechanics behavior and the mechanical parameters that have a critical impact on the hydraulic fracturing propagation, improved decision making in terms of fracturing design and optimization was made. Software was used to model the propagation of hydraulic fractures based on the integrated reservoir mechanical properties analysis. Different scenarios of perforation clusters were run to model propagation of multiple horizontal fractures and predict the changes in stress anisotropy in the neighborhood of the fractures. Results revealed that an increased number of perforation clusters attributed to increased stress interference from the outer fractures, causing reduced inner fracture half-length and resulting in longitudinal fracture propagation rather than transverse fractures, thus reducing the stimulated reservoir volume. The results of this study improve the understanding of the Apollonia reservoir mechanical properties and help provide valuable insight into optimization of multistage hydraulic fracturing design in horizontal wellbores, thus establishing the base for subsequent reservoir development.
During the past few years, Khalda Petroleum company (KPC) are looking forward to significant steps toward improving the economic performance of hydrocarbon producing wells in the low-permeability, heterogeneous reservoirs through the application of high impact technologies used in unconventional wells for drilling, perforating, zonal isolation, fracturing and flowback that unquestionably helped improve well performance in an efficient and economical manner. Recently, the well architecture was changed from vertical completion profile to horizontal multistage fracturing, to increase the reservoir contact. This paper reviews and discuss the well completion and stimulation methods being implemented in horizontal wells fracture stimulation in Western Desert of Egypt allowing for multistages to be fractured in one continuous pumping operation including plug-n-perforation, cemented sliding sleeves with degradable isolation drop balls and Coiled tubing deployed abrasive jetting perforating on coiled tubing with annular path pumping of the fracturing treatment and sand plug isolation. This paper provides a comprehensive evaluation and comparison of these different techniques including an overview of these completion types, detailed engineering, post-stimulation flowback/clean out, discuss the benefits and considerations, and comparison of results from the multistage stimulation methods that were applied to improve the efficiency of multistage fracturing operations. Case histories are provided to support the obtained benefits and advantages, and lessons learnt are discussed along with recommendations and what to avoid in field operations. The case history will discourse the completion strategy, operational procedures, adeptness of the isolation and time frame used. On the other hand, operational setbacks encountered during the execution of the multistage fracturing treatment will also be encompassed in the paper; to allow for future improvement; and recommendations for future field operations to achieve faster fracturing and quicker production.
The key challenge in unconventional gas plays covering vast geographical areas is locating the regions in the reservoir with the highest combination of reservoir and completions quality. This allows operators to evaluate not only the richness of their resource but also the ability of the reservoir to produce hydrocarbons in commercial quantities. This paper discusses hydraulic fracturing designs targeting tight gas in horizontal wells drilled in the Apollonia tight chalk formation in the Abu-Gharadig basin, Western Desert, Egypt through the integration of laboratory, geological, petrophysical, geomechanical, fracture simulation, and diagnostic fracture injection test (DFIT) analysis. Laboratory testing, which included scanning electron microscopy (SEM) and X-ray diffraction (XRD), was conducted to determine mineralogy and potential damage mechanisms. Fracturing fluid chemistry was tested and optimized using core plugs from representative reservoir rock (fracture conductivity, fracturing fluid compatibility, surfactant type, fracture regain permeability, and scale tendency). Geomechanical rock properties derived from advanced petrophysical analysis of newly acquired highdefinition triple-combo full-wave sonic logs and core samples were combined with geological parameters and potential treating schedules to develop sophisticated fracture simulation models. These models were then refined with in-situ reservoir data obtained from DFIT analyses to derive the final fracturing treatment design. The stimulation model was built using a three-dimensional (3D) geological model with multidisciplinary inputs, including formation properties, in-situ stresses, natural fractures, and completion parameters (i.e., well orientation, stage and perforation cluster spacing, fluid volume, viscosity, and proppant volume, size, and ramping schedule). The integration of all available data resulted in an optimized fracture design that helped reduce both cost and formation damage, thus improving flowback, long-term productivity, and profitability from this tight formation.
Most of Egypt's Western Desert reservoirs are characterized to have low permeability and heterogeneous, poor rock quality. In the early development stages only layers with high permeability were produced, while the low-permeability, low-porosity layers were not considered economic.
As these high-permeability layers became more mature and declined in production, tight layers became the operator's alternative choice to unlock the enormous amounts of hydrocarbons still present in these rocks and achieve economical production targets from these marginal fields. Hydraulic fracturing technology enabled us to unlock the potential of these challenging layers that were previously considered uneconomical.
Hydraulic fracturing is now a common practice, even pushing extremes such as deeper, high-temperature and high-pressure wells in the Western Desert. The incremental production gains from these challenging layers have encouraged operators to invest. Currently, hydraulic fracturing is routinely conducted for all new production and injection wells and is reconsidered for the old wells.
Completion practices, candidate selection criteria, perforation and design strategies, and workflows were revised to address these new challenging conditions and reservoir complexities with hydraulic fracturing technology. For example, vertical completions were replaced by horizontal multistage fracturing completions to increase the reservoir contact. State-of-the-art software was used to simplify decisions on fracture initiation points across heterogeneous reservoirs. Different technologies, alternative to conventional perforating, were introduced to enhance the proppant placement, post-fracturing production, and operational efficiency. This paper provides a review of hydraulic fracturing in Egypt's Western Desert. The hydraulic fracturing technique has been used to develop mature fields and challenging formations of Egypt since the early 1990s. More than 1,000 treatments targeting low- to medium- permeability rocks were pumped in Khalda Ridge. Correlation between mechanical properties, reservoir properties, essential fracturing design, completions, and operational parameters were established over time to help other operators that intend to apply hydraulic fracturing to their assets. Case histories are also provided, demonstrating different fracturing techniques for extreme conditions. In this paper we detail the progress related to completion practices and technologies to revive the mature fields of Egypt.