|Theme||Visible||Selectable||Appearance||Zoom Range (now: 0)|
Zeng, Lingping (Curtin University) | Iqbal, Muhammad Atif (Curtin University) | Reid, Nathan (CSIRO) | Lagat, Christopher (Curtin University) | Hossain, Md Mofazzal (Curtin University) | Saeedi, Ali (Curtin University) | Xie, Quan (Curtin University)
Megalitres of water with associated dissolved oxygen are injected into shale reservoirs during the hydraulic fracturing process. Pyrite oxidation, if it occurs
The spontaneous imbibition tests show that the salinity of fluids in ambient conditions is higher than the limited or vacuumed saturation fluids, confirming that pyrite oxidation generates H+ which would dissolve minerals such as calcite and dolomite. This result is also supported by the observed pH and the concentration of dissolved Ca2+. The fluid fully saturated with O2 has the lowest pH and highest Ca2+ compared to limited O2 saturation condition and degassed condition. Scanning electron microscopy analyses show that brine saturation barely affects the morphology and elemental distribution of pyrite at ambient conditions, suggesting that pyrite oxidation plays a minor role in fluid salinity. Geochemical modelling also indicates that although pyrite oxidation can slightly increase fluid salinity, the salinity increment is less than 5% of reported flowback water salinity, confirming that the dissolved O2 in hydraulic fracturing fluids has a minor effect on fluid-rock interaction thus the salinity increment. This work demonstrates that pyrite dissolution at lab-scale would overestimate the impact of fluid-shale interactions and calcite dissolution in reservoir conditions. We prove that pyrite dissolution in
Propellant enhancement is a method of increasing permeability through the application of a transient high pressure event to the target formation. As distinct from hydraulic fracturing, propellant enhancement does not involve the application of chemicals or water and consequently does not present the potential for legacy environmental issues. This paper compares the regulatory aspects of propellant enhancement within the states of Australia and also the differences between environmental impacts.
A series of propellant enhancements were undertaken for a suite of gas wells in the Surat Basin, Queensland. Propellant charges in the range 18-30 kg were initiated, with deflagration times in the range 500-1,000 milliseconds. The compliance regime for the transport, storage and use of propellant is established under the state’s
There are three categories of fracturing used to increase permeability: explosive fracturing; hydraulic fracturing; and propellant enhancement. Explosive fracturing applies a very high pressure transient over a period of a few microseconds and can cause local, radial fracturing but with less desired compaction; hydraulic fracturing applies a lower pressure but over a longer period and with greater surface power, resulting in fractures that can extend 200-300 m, largely in the vertical plane; and propellant enhancement, which applies a mid-range pressure over a period of 10-1,000 milliseconds, resulting in fractures extending tens of metres but with random distribution. Residuals from the deflagration process are nitrogen, hydrogen chloride, water and carbon dioxide. There are no precursors for the BTEX suite and no conditions arising that could produce BTEX.
A prime question was to determine whether propellant enhancement is captured under the term ‘hydraulic fracturing’ in states’ regulations across Australia. Propellant enhancement is a technology with very few environmental impacts. Vehicular movements to support propellant enhancement are less than five percent of those to undertake hydraulic fracturing on the same formation. There is no requirement for waste water treatment.
He, Youwei (Southwest Petroleum University) | Guo, Jianchun (Southwest Petroleum University) | Tang, Yong (Southwest Petroleum University) | Xu, Jianliang (Geological Exploration and Development Research Institute, CNPC Chuanqing Drilling Engineering Co. Ltd.) | Li, Yanchao (Shale Gas Exploration & Development Project Department, CNPC Chuanqing Drilling Engineering Co. Ltd.) | Wang, Yong (Geological Exploration and Development Research Institute, CNPC Chuanqing Drilling Engineering Co. Ltd.) | Lu, Qianli (Southwest Petroleum University) | Patil, Shirish (King Fahd University of Petroleum & Minerals) | Rui, Zhenhua (Massachusetts Institute of Technology) | Sepehrnoori, Kamy (The University of Texas at Austin)
Severe fracturing interference in multi-well pads has been identified in shale gas reservoirs. The gas production of affected multi-fractured horizontal wells (MFHWs) decrease a lot and is hard to restore for most wells even after fracturing fluid flowback. Currently, well interference caused by fracturing operations has become the most important factor affecting the shale gas production. However, the mechanism of fracturing interference and its quantitative impact on gas production in shale gas reservoir are not clear.
The aim of this work is to assess the mechanism and dominated factors of fracturing interference of multi-well pads in shale gas reservoirs, and evaluate the impact of interwell fracturing interference on shale gas production. Firstly, field data in WY Basin are applied to calculate the ratio of impacted wells to newly fractured wells and understand the influencing degree and recovering degree of gas production. The main controlling factors of fracturing interference are determined and the interwell fracturing interacting types are presented. Furthermore, the production recovering potential for impacted wells are analyzed. Finally, some suggestions for mitigating fracturing interference are provided.
The impact degree and recovering degree of gas production are divided into three categories. The dominated factors of fracturing interference include well spacing, pressure of the affected wells before interference, gas production before interference, and flowback ratio of fracturing fluid. The influencing degree of gas production can be estimated by using the generated equations of impact degree of gas production per well spacing (IDGPs) or impact degree of gas production per flowback ratio (IDGPf) Another novel finding is that 70% of affected parent wells belong to adjacent well pad compared with the newly fractured child well. The interwell fracturing interference is divided into four types, including pressure interference without direct communications between two MFHWs (Type I), fracturing interference through natural fracture/secondary fractures (Type II), fracturing interference through hydraulic fractures (Type III), and direct communication between hydraulic fractures and wellbore of adjacent well (Type IV). Fracturing communication through hydraulic fractures or secondary/natural fractures are more common, and the impact on well safety and production performance increases from Type I to Type IV. Therefore, the fracturing parameters need to be optimized to reduce the fracturing interference. This study can provide reasonable suggestions for infill well optimization, fracturing design, and interwell fracturing interference mitigation to achieve the highest gas recovery of all multi-well pads in shale gas reservoirs.
This one-day training event introduces completion, production, surveillance and reservoir engineers to the design of fiber-optic DTS (distributed temperature sensing) and DAS (distributed acoustic sensing) well installations. A basic understanding of the principles and benefits of DTS, DAS and surveillance monitoring technology, in general, is assumed. This course provides both an overview of water management and an in-depth look at critical issues related to sourcing (acquiring), reusing, recycling, and disposing of water in hydraulic fracturing operations. The course starts with a background of hydraulic fracturing operations and the different plays around North America. Options being used for transport, storage, reuse, and disposal are described for each of the different regions.
Aimed at sharing the unconventional wisdom gained from a hydraulic fracturing monitoring case study in the Montney tight gas play, the work showcases the ability of 4D modeling of collective behaviors of microseismic events to chase the frac fluid and navigate the spatiotemporal fracture evolution. Moreover, microseismicity-derived deformation fields are integrated with volumetric estimates made by rate transient analysis to calibrate spatially-constrained SRV models. Through the case study, we give evidence of fracture containment, evaluate the role of natural fractures and the use of diverting agents, estimate cluster efficiencies, conduct analytical well spacing optimization, model productivity decline induced by communication frac-hits from offsets, and provide contributing fracture dimensions and numerical production forecasts. To support the interpretations, we supplement the work by the results of 3D physics- based analytical modeling and multi-phase numerical simulations, and the findings are then validated using two extensive datasets: production profiles acquired by fiber optic DAS, and reservoir fluid fingerprints extracted from mud logs. Besides describing the evolution of seismicity during the treatment, the applied integrated fracture mapping process gives a more reliable and unique SRV structure that streamlines forward modeling and simulations in unconventional reservoirs as well as contributes to solving inverse problems more mechanistically.
Understanding water-rock interactions occurring during hydraulic fracturing is vital to better engineer the hydraulic fracturing water. In this study, a systematic model of water-rock reactions is presented to mimic the interaction of reservoir rock with water.
To investigate the water-rock interaction Marcellus Formation was selected. The reservoir rock samples from the Marcellus Formation were first characterized for its mineral composition by an X-ray diffraction (XRD) and for its elemental composition by an X-Ray fluorescence (XRF). Based on XRD results 3 major minerals were found in Marcellus shale; quartz, calcite, and illite. Later, these minerals with high purity content was ordered from an external chemical company to prepare pseudo rock samples and single-, two-, and three- component mineral-deionized water systems were prepared. The supernatant of these solutions were analyzed for their pH, total dissolved solids (TDS) content, particle size of the colloidal system, and zeta potential of the colloidal systems.
For single-component mineral-water systems, it has been observed that pH and TDS in general give a linear relation with the mineral concentration. For two component mineral-water systems, these relations got weaker and for the three-component systems, only TDS gives good linear relation to the mineral concentration at room temperature. When the experiments repeated at 75 °C to see the effect of temperature on dissolution of minerals in a single-component system, no difference was observed in the linear relations, however, it has been observed that particle sizes of the colloidal systems for all single-component mineral-water system correlates with the TDS content of the water. It should be noted that while particle sizes measure in water gives an idea of the average size of the suspended particles in water, TDS provides information on the dissolved molecules or ionized particles in water. Moreover, we observed that for all experimental data regardless the temperature that we collected them, the TDS concentration decreases with the increase in pH.
Our results for the first time link dissolved matter concentration in water (TDS) with the colloidal system parameter (particle size) and provide an insight on how the colloidal system (suspended solids in water) can affect TDS concentration.