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Collaborating Authors
Perforating
Copyright 2012, Society of Petroleum Engineers This paper was prepared for presentation at the SPE Middle East Unconventional Gas Conference and Exhibition held in Abu Dhabi, UAE, 23-25 January 2012. This paper was selected for presentation by an SPE program committee following review of information contained in an abstract submitted by the author(s). Contents of the paper have not been reviewed by the Society of Petroleum Engineers and are subject to correction by the author(s). The material does not necessarily reflect any position of the Society of Petroleum Engineers, its officers, or members. Electronic reproduction, distribution, or storage of any part of this paper without the written consent of the Society of Petroleum Engineers is prohibited.
- Asia > Middle East > UAE > Abu Dhabi Emirate > Abu Dhabi (0.54)
- North America > United States > Texas (0.48)
- Well Completion > Hydraulic Fracturing > Fracturing materials (fluids, proppant) (1.00)
- Well Completion > Completion Installation and Operations > Perforating (1.00)
Abstract Technological advances and improved operational efficiency have made unconventional resources around the globe far more lucrative for producers. The challenge in recovering hydrocarbons from unconventional resources is low permeability, making it essential that a cost-efficient fracture-stimulation treatment program be performed. However, while the wells being completed are economical, are operators truly capitalizing on their full potential? The process of fracturing unconventional reservoirs has remained virtually unchanged in recent years. Stimulation treatments are pumped at high rates through multiple perforation clusters over a large interval and isolated using mechanical plugs. This poses several problems: Uncertainty of the number of fractures created. Uncertainty of proppant placement into fractures. Costly and time-consuming recovery from screenouts. Pumping plugs results in overflushing the near-wellbore. Treatment changes cannot be seen at the perforations until a casing volume is pumped. Increased cost, footprint, personnel, and hydraulic-horsepower (HHP) requirements. This paper presents a high-rate coiled tubing (CT) fracturing technique that enables customized fracture treatments to help maximize stimulated reservoir volume (SRV) by manipulating flow rate and proppant concentration at the perforations in response to reservoir pressure. Therefore, every gallon of fluid and every pound of proppant can be used to effectively stimulate the formation. Recovery from screenouts is fast because of having coil in-hole, but the functionality of the process enables screenouts to be avoided all together. At the end of the treatment, the well is simply cleaned out, and the entire operation is completed with only one trip in hole and with no plugs to be drilled out. These benefits combined can maximize return on investment for the operator. This paper includes a side-by-side comparison of this technique with a conventional fracturing treatment, weighing risk, stimulation effectiveness, operational efficiencies, and cost savings.
- Well Completion > Hydraulic Fracturing > Fracturing materials (fluids, proppant) (1.00)
- Well Completion > Completion Installation and Operations > Perforating (1.00)
Abstract In 2009, a service company performed its first hydraulic fracturing treatment using a conventional hydraulic-fracturing technique in coalbed methane (CBM) wells in India. As progress was made, the potential for performing an extensive number of hydraulic-fracturing treatments in CBM wells was observed. From an operational standpoint, the advantages of recovering CBM wells are that they have more target coal seams at shallower depths that are candidates for stimulation, and the size of the treatments makes them ideal for multiple applications in a shorter period of time, reducing nonproductive time (NPT) for the operating company (Seldle and Arri 1990). The service company introduced a unique fracturing service that integrated two components—coiled-tubing (CT) deployed hydrajet perforating and then immediately performing hydraulic fracturing. By combining these two processes into one continuous service operation it eliminates the use of wireline for perforating and plug setting, making the new multistage technology economical for CBM wells. For the first time in India, this CT perforating/fracturing service was introduced to a CBM well operator. The observations and knowledge gained from the fracturing-service operations in India are discussed in this paper. This process employed hydrajetting technology through CT using a hydrajetting tool in the bottomhole assembly (BHA). Based on the casing specifications, cementing conditions, rock properties, and experience gained with each perforating experience, the jetting flow rates, differential pressures, and casing annulus backpressure requirements were optimized. This increased the life of the tool and improved the overall operations. The hydrajetting tool life was increased from 6 to 8 perforation sets to about 19 to 21 per tool, improving the operational efficiency. The advantages of jetting acid into the created perforations, pressure squeezing with acid, and using the many services of CT are examined. In addition, the BHA is also discussed. In some of the frac stages, the treatment screened out and experienced high concentrations of sand in the wellbore; therefore, the steps taken to help prevent sanding off the tool or getting the CT stuck are reviewed. Sand concentrations of 12 lbm/gal. were achieved for extended periods of time to pack the formations off. The need for using wellbore sand plugs was eliminated for many frac stages in these wells as a result of successfully packing the proppant into the fractures with higher sand concentrations. This helped eliminate concerns of losing fluid and sand into previous fractures when performing new frac stages uphole. As more treatments were executed and experience was gained, fluid usage was optimized and the fluid consumption was reduced by approximately 30 to 40%, providing further value to the operator. Finally, the lessons learned from a project- management viewpoint are also examined, discussing streamlining operations based on the various field and reservoir conditions experienced in India. The knowledge gained from this project could be directly applicable to the fracturing-service operations in other regions with CBM wells. The operational learnings during the course of this project could also serve as a guide to operations in this region where similar challenges are encountered.
- Asia > India (1.00)
- North America > United States > Texas (0.46)
- North America > Canada > Alberta (0.28)
- Well Completion > Hydraulic Fracturing (1.00)
- Well Completion > Completion Installation and Operations > Perforating (1.00)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Coal seam gas (1.00)
Productivity Increase Using Hydraulic Fracturing in Conventional and Tight Gas Reservoirs – Expectation vs. Reality
Rahim, Zillur (Saudi Aramco) | Al-Anazi, Hamoud (Saudi Aramco) | Al-Kanaan, Adnan (Saudi Aramco) | Habbtar, Ali (Saudi Aramco) | Al-Omair, Ahmed (Saudi Aramco) | Senturk, Nejla (Saudi Aramco) | Kalinin, Daniel (Schlumberger)
Abstract Hydraulic fracturing technology is widely used to facilitate and enhance the gas recovery process from conventional and tight gas resources. Tight gas or unconventional reservoirs, that include very low permeability sandstones, carbonates, or shales, cannot be economically produced without hydraulic fracturing. Recently, much progress has taken place in the overall hydraulic fracturing procedures and the field implementations of advanced stimulation technology have produced good results. The proper selection of well trajectory, gel concentration, polymer loading, proppant type/size and concentration, perforation methods, locations for packer and frac port placement in a multistage fracturing assembly, number of fracture stages to cover the net pay, etc., have all contributed to successful stimulation and improved gas recovery. Even though stimulating gas reservoirs has become a routine application and much experience has been gained in this area, not all treatments are straightforward without problems and challenges. Unless a stimulation treatment is carefully designed and implemented, the post-stimulation results in moderate to tight reservoirs may not be encouraging, and can easily fall below expectation. The most essential step to close the gap between expected results and actual well performance is to understand reservoir characteristics and its potential to produce at a sustained rate after a successful fracturing treatment. Overestimation of reservoir flow capacity and achieved fracture geometry will also over-predict well performance. This paper addresses the importance and impact of detailed reservoir characterization and superior stimulation processes on final well performance. Several field examples from Saudi Arabia’s gas reservoirs are presented in the paper showing the value of effective well planning, reservoir characterization, application of hydraulic fracturing, and proper cleanup. The paper also illustrates the impact of drilling trajectory and wellbore reservoir connectivity on the proper placement of desired hydraulic fracture treatments and sustained gas production.
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.48)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.34)
- Well Completion > Hydraulic Fracturing > Multistage fracturing (1.00)
- Well Completion > Hydraulic Fracturing > Fracturing materials (fluids, proppant) (1.00)
- Well Completion > Completion Installation and Operations > Perforating (1.00)
- (6 more...)
Abstract The appraisal of deep tight gas reservoirs can be technically and economically challenging, with success dependent on applying the most efficient completion technology. Inevitably, this includes designing well completions that encompass the deployment of multiple hydraulic fracturing treatments. There is a tendency in the completion design phase to under-assess the number and variety of interventions that a well could undergo during its evaluation. Subsequently, the development and application of the appropriate well intervention strategy is crucial in maximizing the well potential and reservoir understanding. The deliverable of any tight gas appraisal program is to increase the level of confidence in continuing to pursue the resource opportunity by demonstrating stable and sustainable gas inflow flow rates. Recent drilling success targeting deep frontier gas reservoirs, such as the Amin located in the central part of Oman, have resulted in the need to evolve the well intervention process to include several new (for the region) technologies. These included the deployment of abrasive perforating to facilitate the initial formation breakdown operations, milling out the shoe track for a hydraulic fracturing treatment in an openhole setting, restoring full wellbore access by milling out multiple frac plugs, and temporary installation of a velocity string to eliminate liquid loading issues. Historically, many of these individual processes have been attempted or deployed with varying levels of success, but this is the first time that they have been integrated into a well strategy. This paper summarizes the process of selecting the best options for well intervention operations in low-permeability gas reservoirs. The integrated work design consideration and results of these completion techniques will be presented along with the key learnings derived from the process.
- North America > United States > Texas (0.47)
- Asia > Middle East > Oman (0.36)
Abstract In 2009 Petroleum Development Oman LLC (PDO) started an ambitious tight and deep gas exploration programme exploring for previously untapped reservoirs. The exploration strategy is focusing on both conventional tight gas plays as well as deep unconventional gas resources. These resources are typically in previously undrilled formations at great depths, with high temperatures and unknown pressure regimes, and uncertain fluid fill and composition. The unique geological properties of this type of reservoir require different strategies and technology deployment in order to make them viable and sustainable. With unique geomechanical, reservoir, and geological properties, some of the large gas-bearing prospects within the Fahud Basin in the Sultanate of Oman require innovative drilling and completion practices. A revised drilling and completion workflow, with specific technology deployment and operational flexibility, has been developed in order to account for such reservoir complexity. This workflow includes the incorporation of rock strength acquisition and stress state of the reservoir prior to completion, in order to identify targets for hydraulic fracturing and quantify hydraulic fracturing performance versus reservoir deliverability. The unparalled challenges encountered whilst exploring for these resources required resolving to new technologies from outside the region and adapting them to local conditions. This paper demonstrates the need of integrating various unconventional data sources to enhance the chance of successful reservoir characterization that leads to better understanding of presence of hydrocarbons and reservoir quality. It will also show that classical evaluation methods fail and will not lead to unambiguous interpretations. Recent experience has shown that several independent data sources need to be applied to confidently evaluate well results. The successful application of a technology plan covering aspects of geomechanics, well completions, perforation and formation breakdown, hydraulic fracture placement and treatment yielded positive results that will be of interest to other regional operators facing similar challenges.
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Sedimentary Geology > Depositional Environment > Continental Environment (0.47)
- Geophysics > Borehole Geophysics (1.00)
- Geophysics > Seismic Surveying > Passive Seismic Surveying > Microseismic Surveying (0.71)
- Asia > Middle East > Oman > Fahud Salt Basin (0.99)
- Asia > Middle East > Oman > Dhofar Governorate > South Oman Salt Basin > Amin Field (0.89)
- Asia > Middle East > Oman > Al Wusta Governorate > South Oman Salt Basin > Nimr Field (0.89)
- Well Drilling > Wellbore Design > Wellbore integrity (1.00)
- Well Completion > Hydraulic Fracturing (1.00)
- Well Completion > Completion Installation and Operations > Perforating (1.00)
- (8 more...)