The Study and Field Applications of Hydraulic Fracturing Technology In Clay-Carbonate Reservoirs With High Temperature, Deep Well Depth and densely distributed Natural Fractures

Author(s):  
Tingxue Jiang ◽  
Yiming Zhang ◽  
Yongli Wang ◽  
Yunhong Ding ◽  
Ning Luo ◽  
...  
2022 ◽  
Author(s):  
Liao Wang ◽  
Bo Cai ◽  
Wentong Fan ◽  
Zhanwei Yang ◽  
Guowei Xu ◽  
...  

Abstract Well K1002 is the first highly deviated ultra-deep well in Tarim Oilfield of China, with the reservoir depth 7060m and the well deviation of 60° ∼ 77.6° in the fractured interval. Because of large deviation angle, high breakdown pressure and in-situ stress, poor effectiveness of natural fractures, large reservoir thickness, it is difficult and risky to implement hydraulic fracturing. In this paper, the fractured well was taken for a case study to illustrate the holistic optimization to guarantee the treatment success, a world-wide difficulty with high engineering risk. For figuring out a reasonable treatment design, comprehensive lab experiments and numerical simulation were conducted to analyze and benchmark the reservoir characteristics, rock mechanics and geological model. Systematic study on reducing breakdown pressure, development of natural fractures evaluation, multi-size combination of diverting agent, separated layer stimulation and fracture parameters optimization, treatment fluid formulation, proppant screening and operation program were carried out. Considering the wellbore trajectory and rock mechanics characteristics of well K1002, a breakdown pressure prediction model was established to optimize the perforation orientation. The best perforation orientation was 28° and 208°, the worst perforation orientation was 148° and 328°, and the breakdown pressure range was 168-175MPa with 60° phase angle. Combination with "imaging logging (0-3m) + far detection acoustic logging (0-30m) + geomechanics (0-300m)", the comprehensive evaluation and prediction of natural fractures in near wellbore area and far wellbore area were realized. Based on this, the stimulation technology of "mechanical layering + diverting agent" was optimized to connect the fracture development zone in near wellbore and far wellbore area. According to the Tight Packing Theory, the idea of "multi-size particles combination of diverting agent" was put forward. Through the experiment study, the combination of 1-5mm and 5-10mm particles was optimized, and the optimal chart of diverting agent size combination was made under different reservoir temperatures. For the fracturing job, totally 2562m3 KCL weighted fracturing fluid and 159.2m3 ceramic proppant of 40-70 mesh were pumped. The operation parameters were in reasonable agreement with the design. The initial test production was 10 times higher than before. The experience gained in this case study has some guiding significance for improving the success rate of hydraulic fracturing treatments in the highly deviated ultra-deep well and for effectively developing such fractured tight sandstone reservoirs, both theoretically and practically.


2016 ◽  
Author(s):  
Ronald T. Green ◽  
◽  
F. Paul Bertetti ◽  
Nathaniel Toll ◽  
Nicola Hill

2020 ◽  
Vol 10 (8) ◽  
pp. 3333-3345
Author(s):  
Ali Al-Rubaie ◽  
Hisham Khaled Ben Mahmud

Abstract All reservoirs are fractured to some degree. Depending on the density, dimension, orientation and the cementation of natural fractures and the location where the hydraulic fracturing is done, preexisting natural fractures can impact hydraulic fracture propagation and the associated flow capacity. Understanding the interactions between hydraulic fracture and natural fractures is crucial in estimating fracture complexity, stimulated reservoir volume, drained reservoir volume and completion efficiency. However, because of the presence of natural fractures with diffuse penetration and different orientations, the operation is complicated in naturally fractured gas reservoirs. For this purpose, two numerical methods are proposed for simulating the hydraulic fracture in a naturally fractured gas reservoir. However, what hydraulic fracture looks like in the subsurface, especially in unconventional reservoirs, remain elusive, and many times, field observations contradict our common beliefs. In this study, the hydraulic fracture model is considered in terms of the state of tensions, on the interaction between the hydraulic fracture and the natural fracture (45°), and the effect of length and height of hydraulic fracture developed and how to distribute induced stress around the well. In order to determine the direction in which the hydraulic fracture is formed strikethrough, the finite difference method and the individual element for numerical solution are used and simulated. The results indicate that the optimum hydraulic fracture time was when the hydraulic fracture is able to connect natural fractures with large streams and connected to the well, and there is a fundamental difference between the tensile and shear opening. The analysis indicates that the growing hydraulic fracture, the tensile and shear stresses applied to the natural fracture.


2021 ◽  
Author(s):  
S.A. Baloch ◽  
J.M. Leon ◽  
S.K. Masalmeh ◽  
D. Chappell ◽  
J. Brodie ◽  
...  

Abstract Over the last few years, ADNOC has systematically investigated a new polymer-based EOR scheme to improve sweep efficiency in high temperature and high salinity (HTHS) carbonate reservoirs in Abu Dhabi (Masalmeh et al., 2014). Consequently, ADNOC has developed a thorough de-risking program for the new EOR concept in these carbonate reservoirs. The de-risking program includes extensive laboratory experimental studies and field injectivity tests to ensure that the selected polymer can be propagated in the target reservoirs. A new polymer with high 2-acrylamido-tertiary-butyl sulfonic acid (ATBS) content was identified, based on extensive laboratory studies (Masalmeh, et al., 2019, Dupuis, et al., 2017, Jouenne 2020), and an initial polymer injectivity test (PIT) was conducted in 2019 at 250°F and salinity >200,000 ppm, with low H2S content (Rachapudi, et al., 2020, Leon and Masalmeh, 2021). The next step for ADNOC was to extend polymer application to harsher field conditions, including higher H2S content. Accordingly, a PIT was designed in preparation for a multi-well pilot This paper presents ADNOC's follow-up PIT, which expands the envelope of polymer flooding to dissolve H2S concentrations of 20 - 40 ppm to confirm injectivity at representative field conditions and in situ polymer performance. The PIT was executed over five months, from February 2021 to July 2021, followed by a chase water flood that will run until December 2021. A total of 108,392 barrels of polymer solution were successfully injected during the PIT. The extensive dataset acquired was used to assess injectivity and in-depth mobility reduction associated with the new polymer. Preliminary results from the PIT suggest that all key performance indicators have been achieved, with a predictable viscosity yield and good injectivity at target rates, consistent with the laboratory data. The use of a down-hole shut-in tool (DHSIT) to acquire pressure fall-off (PFO) data clarified the near-wellbore behaviour of the polymer and allowed optimisation of the PIT programme. This paper assesses the importance of water quality on polymer solution preparation and injection performance and reviews operational data acquired during the testing period. Polymer properties determined during the PIT will be used to optimise field and sector models and will facilitate the evaluation of polymer EOR in other giant, heterogeneous carbonate reservoirs, leading to improved recovery in ADNOC and Middle East reservoirs.


2021 ◽  
pp. 52-62
Author(s):  
V. P. Ovchinnikov ◽  
O. V. Rozhkova ◽  
S. N. Bastrikov ◽  
D. S. Leontiev ◽  
P. V. Ovchinnikov

The article discusses the main technological processes of well construction for the production of high-viscosity hydrocarbons from productive lowporosity reservoirs with high temperature and pressure conditions, which include shale deposits of Bazhenov formation. According to the results of the review and analysis of existing solutions in the development of this deposits, the following measures were justified and proposed: construction of branched multi-hole azimuth horizontal wells, implementation of selective multi-stage hydraulic fracturing in the productive formation; the use of oil-based process fluids when opening the reservoir, the use of plugging materials for isolation of the reservoir, the hardening product of which is represented by thermally stable hydrate phases (hydrobasic hydrosilicates). Вranched wells have a long horizontal end (about 1 000 meters or more). Only a part of the horizontal section works effectively, which is the basis for the development and application of the staged, both in time and along the strike, hydraulic fracturing method. At the level of the invention, a method and apparatus for carrying out multistage selective hydraulic fracturing in wells with horizontal completion have been developed. The article describes a method for implementing multistage selective hydraulic fracturing, comparing this method with the existing ones. Much attention is given to the need to use hydrocarbon-based solutions for the initial opening the reservoir, to use cement slurries from composite materials to separate the reservoir, the hardening product of which is a stone formed by low-basic calcium hydrosilicate.


2021 ◽  
Author(s):  
Joseph Ferrar ◽  
Philip Maun ◽  
Kenneth Wunch ◽  
Joseph Moore ◽  
Jana Rajan ◽  
...  

Abstract We report the design, operation and biogenic souring data from a first-of-its kind suite of High Pressure, High Temperature (HPHT) Bioreactors for hydraulically fractured shale reservoirs. These bioreactors vet the ability of microbial control technologies, such as biocides, to prevent the onset of microbial contamination and reservoir souring at larger experimental volumes and higher pressures and temperatures than have been previously possible outside of field trials. The bioreactors were charged with proppant, crushed Permian shale, and sterile simulated fracturing fluids (SSFF). Subsets of bioreactors were charged with SSFF dosed with either no biocide, tributyl tetradecyl phosphonium chloride (TTPC, a cationic surface-active biocide), or 4,4-dimethyloxazolidine (DMO, a preservative biocide). The bioreactors were shut in under 1,000-2,500 psi and elevated temperatures for up to fifteen weeks; hydrogen sulfide (H2S) and microbial counts were measured approximately once per week, and additional microbes were introduced after weeks three and five. Across two separate studies, the bioreactors containing no biocide soured within the first week of shut-in and H2S concentrations increased rapidly beyond the maximum detectable level (343 ppm) within the first three to six weeks of shut-in. In the first study, the bioreactors treated with TTPC soured within two weeks of shut-in (prior to the first addition of fresh microbes), and H2S concentrations increased rapidly to nearly 200 ppm H2S within the first six weeks of shut-in and beyond the maximum detectable level after fifteen weeks of shut-in. The bioreactors containing DMO did not sour during either study until at least the first addition of fresh microbes, and higher levels of the preservative biocide continued to prevent the biogenic formation of H2S even during and after the addition of fresh microbes. Microbial counts correlate with the H2S readings across all bioreactor treatments. The differentiation in antimicrobial activity afforded by the different types of biocide treatments validates the use of these simulated laboratory reservoirs as a biocide selection tool. This first-of-its-kind suite of HPHT Bioreactors for hydraulic fracturing provides the most advanced biocide selection tool developed for the hydraulic fracturing industry to date. The bioreactors will guide completions and stimulation engineers in biocide program optimization under reservoir-relevant conditions prior to beginning lengthy and expensive field trials.


Geophysics ◽  
2021 ◽  
pp. 1-97
Author(s):  
kai lin ◽  
Bo Zhang ◽  
Jianjun Zhang ◽  
Huijing Fang ◽  
Kefeng Xi ◽  
...  

The azimuth of fractures and in-situ horizontal stress are important factors in planning horizontal wells and hydraulic fracturing for unconventional resources plays. The azimuth of natural fractures can be directly obtained by analyzing image logs. The azimuth of the maximum horizontal stress σH can be predicted by analyzing the induced fractures on image logs. The clustering of micro-seismic events can also be used to predict the azimuth of in-situ maximum horizontal stress. However, the azimuth of natural fractures and the in-situ maximum horizontal stress obtained from both image logs and micro-seismic events are limited to the wellbore locations. Wide azimuth seismic data provides an alternative way to predict the azimuth of natural fractures and maximum in-situ horizontal stress if the seismic attributes are properly calibrated with interpretations from well logs and microseismic data. To predict the azimuth of natural fractures and in-situ maximum horizontal stress, we focus our analysis on correlating the seismic attributes computed from pre-stack and post-stack seismic data with the interpreted azimuth obtained from image logs and microseismic data. The application indicates that the strike of the most positive principal curvature k1 can be used as an indicator for the azimuth of natural fractures within our study area. The azimuthal anisotropy of the dominant frequency component if offset vector title (OVT) seismic data can be used to predict the azimuth of maximum in-situ horizontal stress within our study area that is located the southern region of the Sichuan Basin, China. The predicted azimuths provide important information for the following well planning and hydraulic fracturing.


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