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Abstract The application of high viscosity friction reducers (HVFRs) in unconventional plays has steadily increased over the past years, not only as alternatives to conventional friction reducers (FRs) but also as a direct replacement for the use of guar-based fluids. HVFRs demonstrate more efficient proppant transport, due to their unique rheological properties, concurrently with a high friction reduction effect allowing higher pumping rates. However, all these benefits come with few critical limitations related to frac water quality, compatibility with other additives, and static proppant suspension, which makes them very similar to conventional crosslinked gels regarding their Quality Assurance and Quality Control (QAQC) requirements at a well location during the field implementation. This paper illustrates the comprehensive laboratory efforts undertaken to evaluate different HVFR and crosslinked gel products, their successful field application supported by a robust and effective field QAQC process, and the critical importance of maintaining effective field-laboratory-field interaction/cycle to optimize the fluid design and maximize the results. Experimental studies on different products were conducted to measure the effect of frac water quality, HVFR loading, breaker loading, and compatibility with other additives used in the fluid recipe such as surfactants, scale inhibitors, and biocides. The ability of HVFR to suspend and transport proppant is not only a function of polymer loading but also highly influenced by fluid velocity as static and semi-dynamic proppant suspension tests demonstrate. Additionally, a full dynamic proppant transport test was also conducted using a multi-branched slot apparatus to simulate the flow inside a complex fracture network. Field execution followed a strict QAQC protocol including water analysis, field laboratory tests, water filtration, mixing procedure, product storage, and transport allowing direct onsite replication of the results that had been previously obtained in the laboratory. Constant communication between the field and the laboratory allowed a successful execution of several treatments in a challenging shale play in the Sichuan Region, China. These treatments achieved record proppant placements and, just as importantly, they demonstrated repeatability and consistency over time; which had not previously been attained. Laboratory testing proved critical in confirming that product segregation was occurring, even if there was no visual observation of this phenomenon, which had resulted in initial difficulties in fluid quality and reliability. The presence of constant QAQC engineering support on location was instrumental in rapidly identifying the potential root cause(s) and efficiently and correctly applying the necessary corrective actions. This paper will highlight the importance of laboratory testing, in order to design and optimize the fluid system. The paper will also demonstrate how critical the onsite QAQC is through actual examples of fluid optimization and field implementation. These two activities, although requiring a substantial resource commitment and effort, are both required to achieve successful execution.
- North America > United States > Texas (1.00)
- Asia > China (1.00)
- Geology > Geological Subdiscipline > Geomechanics (0.93)
- Geology > Petroleum Play Type > Unconventional Play > Shale Play (0.34)
- North America > United States > Oklahoma > Anadarko Basin > Sooner Trend Anadarko Canadian and Kingfisher Play (STACK) > Sooner Trend Anadarko Canadian and Kingfisher Play (STACK) (0.99)
- Asia > China > Sichuan > Sichuan Basin (0.99)
AOF Analysis of One Shale Gas Play
Pang, Wei (Sinopec Research Institute of Petroleum Engineering) | Xin, Cuiping (Research Institute of Shaanxi Yanchang Petroleum (Group) Co., Ltd.) | Du, Juan (Sinopec Research Institute of Petroleum Engineering) | He, Ying (Sinopec Research Institute of Petroleum Engineering) | Mao, Jun (Sinopec Research Institute of Petroleum Engineering)
Abstract China is believed to own the world's largest shale gas reserve and is the third country to exploit shale gas breakthrough in the world. Fuling gas play in Sichuan basin is one typical shale gas reservoir in China gaining good production performance, and the absolute open flow capacity (AOF) of some wells reaches as high as 1.5 million cubic meters per day. However, we still haven't get good understanding of AOF to evaluate the producing potential and performance of hydraulic fracturing in Fuling shale gas play. In order to quantify the influence of parameters on AOF, statistical analyses are conducted on fourteen parameters including formation porosity, total organic carbon (TOC), injected fluid volume, injected proppant volume, injected fluid volume per stage, injected proppant volume per stage, proppant concentration, fractured stages, and fractured clusters, horizontal lateral length, angle between horizontal lateral and minimum stress direction, cumulative production in the first three months, stimulated reservoir volume (SRV) and flowback recovery in the first three months. Results show that six parameters including cumulative gas in first three months, angle between horizontal lateral and minimum stress direction, SRV, TOC, porosity and injected fluid volume show relative strong correlation with AOF with coefficient bigger than 0.50. The influence of the other nine parameters on AOF is very weak, and the coefficient between AOF and water flowback recovery in early days is even as small as 0.11. AOF is negatively correlated to three parameters including proppant volume per stage, proppant concentration, and angle between horizontal lateral and minimum stress direction. The negative influence of proppant concentration on AOF may have been caused by ineffective fractures (networks), and a positive correlation can be expected if proppants are injected into "sweet points" that meet the geology and engineering requirements and improved stimulation techniques with better performance of fracture propagation control. The angle between horizontal lateral and minimum stress direction is suggested to be less than 20ยฐ in order to get bigger AOF. AOF is positively correlated to the other eleven parameters. High TOC, porosity, injected fluid volume are good indication of high AOF.
- North America > United States > Texas (0.29)
- Asia > China > Sichuan Province (0.26)
- Energy > Oil & Gas > Upstream (1.00)
- Government > Regional Government > North America Government > United States Government (0.30)
- North America > United States > Texas > West Gulf Coast Tertiary Basin > Eagle Ford Shale Formation (0.99)
- North America > United States > Texas > Sabinas - Rio Grande Basin > Eagle Ford Shale Formation (0.99)
- North America > United States > Texas > Maverick Basin > Eagle Ford Shale Formation (0.99)
- Asia > China > Sichuan > Sichuan Basin (0.99)
- Well Completion > Hydraulic Fracturing > Fracturing materials (fluids, proppant) (1.00)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Shale gas (1.00)
Abstract The success of commercial production of shale gas/oil in North America encourages other countries, such as China to replicate the U.S. shale gas revolution. The Sichuan Basin located in southwest of China is one of the largest proven shale formations with complex tectonics compared with US shale plays. The shale has natural fractures and local Earth stress is complex. The high formation stresses make initiating hydraulic fractures difficult. Therefore, very high surface fracturing pressure and high horsepower is needed to perform large scale fracturing jobs and initiate hydraulic fractures. There are two types of shale formations in the Sichuan Basin, one is a lacustrine formation that is not a common formation globally to produce hydrocarbons and the other a marine formation. A couple of appraisal wells have been successfully drilled and fractured with commercial gas production rates in both formations. One horizontal shale gas appraisal well in the lacustrine formation was drilled with 4,102 meters (13,454ft) in total measured depth (MD), 3,088 meters (10,129ft) in true vertical depth (TVD) and 815meters (2,673 ft) in horizontal section. The 10-stage ball-activated sleeves and open hole packers system were chosen as the multistage fracturing completion design. Based upon the research and analysis of this formation, the largest ever shale gas frac operation in China was completed in January, 2013. A total of 265.7m3 (990,000lbs) of proppant and 8625.5m3 (2,278,616 gals) of frac fluid were pumped into the target formation with a maximum surface fracturing pressure of 61MPa (8,847psi) and a pump rate of 12.4 m3/min (77.9 bbls/min). This frac operation set 2 new records in China for the proppant tonnage and the frac fluid volume. This paper will provide a comprehensive view of this successful fracturing operation in the lacustrine formation including formation evaluation, fracturing design and fracturing completion strategy such as determining the optimal number of frac stages per lateral, proppant type and mesh size, volumes of proppant pumped on each stage, fracture completion tool, fracturing fluid type, and injection rate. The success of the fracturing job in this well marks a new breakthrough in gas field exploration in the Sichuan lacustrine formation and provides a guideline for future shale gas frac operations in similar formations or blocks. Introduction Due to rapid development in the last few decades, China is one of the most energy hungry countries in the world. To date, China is still heavily reliant on coal for energy which severely affects pollution, emissions and efficiency. To address these problems, the government has become more and more aware of the need to change energy consumption composition, i.e. reduce coal usage and increase use of natural gas. What is important is that China has great potential for natural gas production, especially for shale gas. In China, compared with marine formations from which a large amount of oil and gas has been produced, very limited attention has been paid to lacustrine formations, such as the Xujiahe formation in Sichuan Basin where there exists good conditions for potential commercial reservoirs. As the shale gas industry in North America has successfully developed and been leading the world, learning from North America is a good choice to accelerate shale gas development for China. Based on these considerations, the well in this case study was intended to be drilled as one of appraisal wells to find out the commercial production potential of the Xujiahe formation and execute a multistage hydraulic fracturing based on applying US technology and experience.
- Asia > China > Sichuan Province (1.00)
- North America > United States > Texas (0.68)
- Phanerozoic > Paleozoic (0.68)
- Phanerozoic > Mesozoic (0.47)
- North America > United States > Texas > Haynesville Shale Formation (0.99)
- North America > United States > Texas > Fort Worth Basin > Barnett Shale Formation (0.99)
- North America > United States > Louisiana > Haynesville Shale Formation (0.99)
- (6 more...)
- Well Completion > Hydraulic Fracturing > Fracturing materials (fluids, proppant) (1.00)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Shale gas (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)