Through data gathering, machine learning, and the use of a supercomputer, a non-profit organization in Texas is seeking to boost oil and gas production on land owned by the states’ two largest university systems. This paper reviews two newly developed novel completion systems that significantly reduce time spent performing multistage stimulation in environments where cost and consequence of failure are high.
Drilling and completion expenditure and activity is projected to show multiyear double-digit growth from 2018–2022 despite a flattening of rig count increases. This paper reports the completion of a two-lateral well in the Williston basin where produced water (PW), filtered but otherwise untreated, was used throughout the slickwater and crosslinked components of approximately 60 hydraulic-fracturing stages.
The Apollonia tight-gas chalk play is located in the Abu Gharadig Basin in the Western Desert of Egypt. This has long been ignored as a gas play in the overburden, while the Jurassic and Cretaceous oil fields deeper in the basin have been explored and developed. Dubai Petroleum embarked on a new mission last year to drill and complete its first multistage, hydraulically fractured, and propped horizontal well from an offshore platform. This paper gives the recommended MSF horizontal-well spacing for several development scenarios in Saudi Arabian gas-reservoir environments. A tight gas carbonate reservoir with no oil rim in a supergiant onshore gas field in Abu Dhabi was targeted for stimulation during a field review to increase field production.
The agency updated its methodology and production volume estimates to factor increasing production from new, emerging plays as well as older plays that have rebounded thanks to drilling advancements. Russia has looked to the east to find more oil and gas, growing markets and investor support, allowing it to shrug off the global slump and trade sanctions. Dubai Petroleum embarked on a new mission last year to drill and complete its first multistage, hydraulically fractured, and propped horizontal well from an offshore platform.
This course gives an overview for completing, fracturing, and refracturing shales and other low-permeability formations that require multistage hydraulic fracturing. Participants will learn the primary types of wellbore completion options, plug-and-perf, ball-activated systems, and coiled tubing-activated systems, and how they compare in different applications. Participants will also learn hydraulic fracturing and refracturing theory and design, including slick-water fracturing, cross-linked gels, fluids, proppants, additives, refracturing options, and identifying refracturing candidates. In the last decade new production from shales and other low-permeability reservoirs that require multistage hydraulic fracturing has significantly influenced the price and supply of hydrocarbons. The success of these plays in North America has operators around the globe trying to identify similar reservoirs.
Pressure transient analysis (PTA) has been one of the primary means for qualitative and quantitative assessment of hydraulically fractured wells for the last few decades. With the advancement of technology, more complex hydraulic fractures are being created for increased contact area. Recently horizontal wells multi-stage fracturing (MSF) for tight gas reservoirs has been gaining popularity. Flow regimes and therefore the derivative response of the transient pressure data is dependent on the achieved fracture geometry, which is also stress field dependent. These responses can be very complex and difficult to interpret. An insight of the possible flow regimes is a pre-requisite to computing reservoir and fracture properties. In the absence of other information or proper planning, a unique interpretation of PTA data is almost impossible.
In this paper we first examine the theoretical basis of various transient pressure response trends for various hydraulic fracturing geometry. Then we present some practical challenges involved with the qualitative and quantitative interpretation of transient pressure response of various MSF geometries. We draw from the results of about a dozen field examples with actual data depicting realistic outcome of PTA of this completion type. Finally we enumerate the additional data gathering requirements to improve qualitative and quantitative interpretation of transient pressure response of MSF wells.
Transient pressure data analysis still remains the primary means of assessing MSF completions effectiveness. The horizontal well direction relative to the maximum or minimum stress controls the fracture geometry resulting in distinctly different flow regimes. Because of the low permeability of the MSF candidate wells, achieving the far reservoir radial flow is very time consuming, expensive and signal to noise ratio may become too poor. A pre-job PBU test of the pilot hole to define flow capacity of the target reservoir sheds a lot of light on the final interpretation of MSF wells pressure transient data.
The demand for unconventional gas is rapidly increasing to provide enough energy to maintain sustainable growth for industrial countries. Even oil producers can develop UG to be directed to internal industrial and power consumptions. As Unconventional gas reservoirs are located in deep high-stress formations, one of the critical challenges gas producers are facing is to develop a cost effective stimulation method that can reduce production cost to lower than Break-even.
In this paper a novel stimulation method, based on thermochemicals, is introduced. Thermochemicals when injected in tight reservoirs generate localized pressure-pulses, which result in creating microfractures, improve permeability and increase stimulated reservoir volume (SRV). Tight core samples were treated with thermochemicals and the impact on mechanical properties were studied. Generated localized pressure was clearly detected during Coreflood treatment. Microstructural and mineralogical properties were also investigated using microscopy and spectroscopy. CT-scan, micro CT-Scan, Young's modulus, Poisson's ratio and ultrasonic velocities were measured pre and post treatment. Results showed creation of fractures and microfractures, which resulted in improved rock conductivity.
Results show that, micro-factures are created inside the used sample due to the in-situ generation of heat and pressure. The density of those micro-factures is strong function of the chemical concentration and the injected volume. Creation of micro-factures leads to improve the formation conductivity and reduce the capillary forces, therefore, enhances the hydrocarbon recovery. The outcome of this study is to understand the impact of thermochemical treatment on rock integrity. The ultimate objective is to establish a relationship between the injected chemicals and the alterations of formation properties such as permeability and porosity. This work will serve as a baseline for designing and conducting thermochemical operations for hydrocarbon reservoirs.
In this study a novel stimulation technique to increase stimulated reservoir volume (SRV) is presented. In basins with excessive tectonic stresses, the current novel treatment can become an enabler to deeply stimulate well stages which otherwise left untreated. A new methodology is developed to lower fracturing cost and increase unconventional gas production. A better connectivity reduces the required number of hydraulic fracturing-stages.
Today, when most reservoirs have low productivity, the question of whether hydraulic fracturing can be applied to the oil rims becomes very important. During hydraulic fracturing at Novoportovskoe field, the operator was faced with a complex geological model of the reservoir characterized by an absence of strong barriers and minor contrasts in stress between interlayers associated with high risks of breakthrough into the gas zone. An outstanding example of oil rim stimulation and application of new technology was a project in Novoportovskoe field where 30-and 27-stage multistage fracturing operations (MSF) were successfully performed with a shifting ports completion operated by coiled tubing. Currently, oil and gas companies are increasingly demanding technical and technological aspects of the MSF, where the determining factors are the efficiency of operations, the number of stages, the length of the horizontal part of the well, the possibility of refracturing, and ability to open / close sleeves after operation for water and gas shut-off. The experience gained shows the possibilities of modern technologies, where the use of coiled tubing enables meeting the high requirements and also expanding the boundaries of the application. The 30-stage boundary was successfully overcome and allowed to increase the formation coverage by means of more fracturing stages. At the same time, the completion method made it possible to perform MSF without pulling the coiled tubing out of hole and to use all the capabilities and benefits of CT in the case of a screenout (SO). The teamwork between the customer and several of the contractor's product lines enabled successful completion of the integrated project under the difficult geological and climatic conditions of the Novoportovskoe field, which is located beyond the Arctic Circle. An optimized concept of MSF with the use of re-closable full-pass hydraulic fracturing sleeves, operated by a single-trip coiled tubing-conveyed shifting tool was developed and implemented.
Sayapov, Ernest (Petroleum Development Oman) | Nunez, Alvaro Javier (Petroleum Development Oman) | Al Salmi, Masoud (Petroleum Development Oman) | Al Farei, Ibrahim (Petroleum Development Oman) | Gheilani, Hamdan (Petroleum Development Oman) | Benchekor, Ahmed (Petroleum Development Oman) | Al-Shanfari, Abdul Aziz (Petroleum Development Oman)
Multistage frac completion (MFC) has been playing a significant role in modern oilfield industry being one of the key tools making development of low permeable formations economical. Commonly, it is applied in horizontal wells that are drilled to compensate for reduced drainage radius of these wells due to a lack of formation conductivity. This technique is evolving, there are quite a few inventions introduced every year that make MFC easier, more economical and that allow the operators to control and precisely evaluate both the treatment itself and performance of the created fractures. However, due to its nature and initial focus on horizontal wells, it did not become very popular in vertical wells. One of the reasons for it is its limited formation access since the sleeves that are providing the access are short and cannot cover the entire net pay. What historically more common in vertical wells are either conventional "plug and perf" approach or its modifications, whereas intervals are perforated with either coiled tubing and sand-blasting perforation or wireline guns, while isolation of the zones is achieved by setting frac plugs, sand plugs or frac packers depending on pumping conduits. In Petroleum Development Oman, some of these vertical wells were stimulated via multistage frac completion.
In central part of the Sultanate of Oman, a deep tight gas field is developed using hydraulic fracture stimulation technique since the formation conductivity is low and the near wellbore damage after drilling is making it even worse. Normally, between 6 and 13 frac intervals are stimulated in each well. Majority of wells are completed vertically with pay zones separated with strong shale layers that restrict fracture height development. Since plug & perf has been the main technique used in this field, there are multiple well interventions during hydraulic fracture operations that consume time, money and delay the well delivery. Moreover, the depletion of the field and its main productive zones make well intervention activities much more challenging whereas the risks of getting coiled tubing string or even wireline tools stuck in wellbore are high due to immediate losses faced after opening those low pressurized zones having as low as 8,000 KPa formation pressure, which can be 5-7 times less than hydrostatic pressures in the wellbore depending on depths and fluid s used. At the same time, with downhole temperatures ranging from 135 to 150 deg C and fracturing pressures reaching around 145,000 KPa bottomhole (~21,000 psi), differential pressures across the target zones can reach enormous levels of 15,000-20,000psi. Conditions in general become very risky, making it extremely difficult to source the right tools and equipment from what is available on the market. Another challenge associated with depletion of this field is an effective deliquification of the wells after stimulation treatments to allow them to effectively get rid of frac fluids and be able to produce gas to surface.
By deploying multistage frac completion with the objective of producing, enhancing and cost/time savings, the effectiveness of the fracturing operations was expected to increase. Multistage frac completion allows the frac operation to be continuously performed without the need to conduct well interventions such as running/setting frac plugs, perforating, milling and clean out between intervals. If needed so, the intervention activities can be completed after frac operations. Equipment selection and completion design were performed based on well conditions, market availabilities, operational parameters and composition of the produced gas. However, this technique is associated with its specific challenges that require attention and tailored solutions. The main challenge in deployment of this system in vertical wells is the accurate positioning of the sleeves. The shale layers between the pay zones could be as narrow as 5 m or less and a small pay zone can be easily missed. Besides, deployment and cementing operations are equally essential because of water zones embedded in between the pays.
This paper is discussing the recognized benefits and lessons learned from utilization of multistage frac completion in vertical deep (around 5000 m) depleted tight gas wells covering the completion and hydraulic fracturing stimulation operations. This technique has industry proven cost & time reduction and efficiency gain, as well as faster well cleanup and reduced HSE exposure contributing to better gas recovery, improvement in operator's performance and energy delivery to the country; it was expected to demonstrate a step change in the efficiency compared to conventional approach to the field development.
Plug and Perf (P&P) still remains one of the most prolific methods used in multi-stage hydraulic fracturing operations. Recent changes in the materials chosen to manufacture frac plugs is leading to increased efficiencies during installation as well as the plug milling phase of P&P operations.
Historically, the fluid diversion devises used in multi-stage hydraulic fracturing operations have been manufactured using mainly glass/epoxy based composite materials and in recent years, in an effort to increase efficiencies, disintegrating materials. Most efforts have been focused on reducing the amount of metallic parts as well as reducing the overall amount of material used to manufacture these plugs in an effort maintain plug performance during fracturing operations while reducing time/costs during post-frac milling operations by making plug removal more efficient.
Recent advances in metallic based composite materials are allowing for plugs to be manufactured out of light weight alloys that are higher strength than traditional composite plug materials while also being easier to remove and circulate out during plug milling operations. Also, because the materials are not designed to disintegrate, there is no need to consider fluids that the plugs will be exposed to thus ensuring a high performance plug without the careful balancing act between an environment that causes the plug to disintegrate too fast or not at all. In addition to this, changes in how slips and packing elements are being designed is allowing for additional gains in efficiencies during plug deployment and removal.
Using real-world results, we can now demonstrate how these design changes can allow for a new level of operational efficiencies not previously available in P&P operations.