Productivity Enhancement in Multilayered Unconventional Rocks Using Thermochemicals

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Zeeshan Tariq ◽  
Mohamed Mahmoud ◽  
Olalekan Alade ◽  
Abdulazeez Abdulraheem ◽  
Ayyaz Mustafa ◽  
...  
Keyword(s):  
Hydraulic Fracturing ◽  
Elastic Moduli ◽  
Cost Effective ◽  
The Novel ◽  
Productivity Analysis ◽  
Breakdown Pressure ◽  
Linear Elastic ◽  
Layered Formation ◽  
Fracture Height ◽  
Fracturing Experiments

Abstract Elastic moduli contrast between the adjacent layers in a layered formation can lead to various problems in a conventional hydraulic fracturing job such as improper fracture height growth, limited penetration in a weaker layer only, and nonconductive fractures. In this study, the results of thermochemical fracturing experiment are presented. The hydraulic fracturing experiments presented in this study were carried out on four-layered very tight cement block samples. The results revealed that the novel fracturing technique can reduce the required breakdown pressure in a layered rock by 26%, from 1495 psi (reference breakdown pressure recorded in the conventional hydraulic fracturing technique) to 1107 psi (breakdown pressure recorded in the thermochemical fracturing). The posttreatment experimental analysis showed that the thermochemical fracturing approach resulted in deep and long fractures, passing through majority of the layers, while conventional hydraulic fracturing resulted in a thin fracture that affected only the top layer. A productivity analysis was also carried out which suggested that the fracturing with thermochemical fluids can raise the oil flowrate up to 76% when compared to a conventional hydraulic fracturing technique. Thermochemical fluids injection caused the creation of microfractures and reduces the linear elastic parameters of the rocks. The new technique is cost effective, nontoxic, and sustainable in terms of no environmental hazards.

The effect of stress on the primary permeability of rock cores—a facet of hydraulic fracturing

1981 ◽  
Vol 18 (2) ◽  
pp. 195-204 ◽  
Author(s):  
R. Heystee ◽  
J.-C. Roegiers
Keyword(s):  
Rock Mass ◽  
Hydraulic Fracturing ◽  
The State ◽  
Stress Conditions ◽  
Breakdown Pressure ◽  
Rock Types ◽  
State Of Stress ◽  
Pressurization Rate ◽  
Fluid Penetration ◽  
Fracturing Experiments

Recent laboratory hydraulic fracturing experiments have shown that fluid penetration into the rock mass adjacent to the borehole being pressurized has a significant influence on the magnitude of the breakdown pressure. One factor affecting the degree of penetration of the pressurizing fluid is the permeability of the rock mass, which in turn is a function of the state of stress present in the rock mass. To study this permeability–stress relationship, a radial permeameter was constructed and three rock types tested. Derived expressions show that during radially divergent and convergent flow in the permeameter, the state of stress in the rock specimen is tensile and compressive respectively. The radial permeameter test results show that the permeability of rock increases significantly under tensile stress conditions and reduces under compressive stress conditions. The results from this study were used to develop a conceptual model which explains the dependency of breakdown pressure levels on the pressurization rate.

Chemically-Induced Pressure Pulse: Fracturing Competent Reservoirs

2021 ◽  
Author(s):  
Ayman R. Al-Nakhli ◽  
Zeeshan Tariq ◽  
Mohamed Mahmoud ◽  
Abdulazeez Abdulraheem
Keyword(s):  
Hydraulic Fracturing ◽  
Rock Fracture ◽  
Applied Pressure ◽  
Hydraulic Fractures ◽  
Breakdown Pressure ◽  
Hydrocarbon Production ◽  
Fracture Pressure ◽  
Micro Cracks ◽  
Chemically Induced ◽  
Fracturing Experiments

Abstract Commercial volumes of hydrocarbon production from tight unconventional reservoirs need massive hydraulic fracturing operations. Tight unconventional formations are typically located inside deep and over-pressured formations where the rock fracture pressure with slickwater becomes so high because of huge in situ stresses. Therefore, several lost potentials and failures were recorded because of high pumping pressure requirements and reservoir tightness. In this study, thermochemical fluids are introduced as a replacement for slickwater. These thermochemical fluids are capable of reducing the rock fracture pressure by generating micro-cracks and tiny fractures along with the main hydraulic fractures. Thermochemical upon reaction can generate heat and pressure simultaneously. In this study, several hydraulic fracturing experiments in the laboratory on different synthetic cement samples blocks were carried out. Cement blocks were made up of several combinations of cement and sand ratios to simulate real rock scenarios. Results showed that fracturing with thermochemical fluids can reduce the breakdown pressure of the cement blocks by 30%, while applied pressure was reduced up to 88%, when using thermochemical fluid, compared to slickwater. In basins with excessive tectonic stresses, the current invention can become an enabler to fracture and stimulate well stages which otherwise left untreated. A new methodology is developed to lower the breakdown pressure of such reservoirs, and enable fracturing. Keywords: Unconventional formation; breakdown pressure; thermochemicals; micro fractures.

A New Generation High-drag Proppant: Prototype Development, Laboratory Testing, and Hydraulic Fracturing Modeling

2015 ◽  
Author(s):  
Yinghui Liu ◽  
Ernesto Fonseca ◽  
Claudia Hackbarth ◽  
Ralph Hulseman ◽  
Kenneth N. Tackett II
Keyword(s):  
Hydraulic Fracturing ◽  
Laboratory Testing ◽  
Cost Effective ◽  
The Novel ◽  
Coverage Area ◽  
Prototype Development ◽  
Lower Viscosity ◽  
New Generation ◽  
Settling Performance ◽  
Half Length

Abstract A new generation alumina ceramic proppant has been developed for higher drag and thus improved settling performance compared to conventional sand or ceramic proppant. Slickwater hydraulic fracture treatments in unconventional gas and tight oil developments are less expensive and less likely to leave residue than cross-linked gel formulations, but due to the lower viscosity, proppant transported with slickwater tends to settle out, likely contributing to screenout of proppant and shorter fracture half length with limited propped height. This novel proppant technology is designed to address the challenges of better proppant placement and increased propped height and half length in slickwater fracturing. This paper describes prototype development of the novel proppant technology, laboratory testing, and hydraulic fracturing modeling. The new proppant is shaped such that it tumbles and flutters during sedimentation in water and this movement greatly reduces settling rate. Finite element structural analysis was conducted to optimize the geometry to achieve higher crush strength while maintaining the conductivity. Laboratory sedimentation tests show a significant increase in settling time of new generation proppant compared to 30-50 sand poppant which had similar size and weight. Hydraulic fracturing modeling shows potential for a significant increase in proppant coverage area. With structurally designed and optimized shapes, this high drag proppant has better transport/placement due to lower settling rates, and enhanced proppant flowback control. Finally, a practical manufacturing process has been identified to enable cost-effective manufacturing of this material.

Simulation of Multiple Hydraulic Fracturing in Non-Uniform Pore Pressure Field

2005 ◽  
Vol 9 ◽  
pp. 163-172 ◽  
Author(s):  
Lian Chong Li ◽  
Chun An Tang ◽  
Leslie George Tham ◽  
Tian Hong Yang ◽  
Shao Hong Wang
Keyword(s):  
Hydraulic Fracturing ◽  
Pore Pressure ◽  
Process Analysis ◽  
Failure Process ◽  
Fracture Initiation ◽  
Global Scale ◽  
Breakdown Pressure ◽  
Failure Evolution ◽  
Rock Failure Process ◽  
Fracturing Experiments

A series of numerical simulations of hydraulic fracturing were performed to study the initiation, propagation and breakdown of fluid driven fractures. The simulations are conducted with a flow-coupled Rock Failure Process Analysis code (RFPA2D). Both heterogeneity and permeability of the rocks are taken into account in the studies. The simulated results reflect macroscopic failure evolution process induced by microscopic fracture subjected to porosity pressure, which are well agreeable to the character of multiple hydraulic fracturing experiments. Based on the modeling results, it is pointed out that fracture is influenced not only by pore pressure magnitude on a local scale around the fracture tip but also by the orientation and the distribution of pore pressure gradients on a global scale. The fracture initiation, the orientation of crack path, the breakdown pressure and the stress field evolution around the fracture tip are influenced considerably by the orientation of the pore pressure. The research provides valuable guidance to the designers of hydraulic fracturing engineering.

scholarly journals Cyclic Injection to Enhance Hydraulic Fracturing Efficiency: Insights from Laboratory Experiments

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Hao Kang ◽  
Jincai Zhang ◽  
Xin Fan ◽  
Zhiwen Huang
Keyword(s):  
Hydraulic Fracturing ◽  
Injection Pressure ◽  
Pressure Amplitude ◽  
Pressure Reduction ◽  
Breakdown Pressure ◽  
Injection Method ◽  
Number Of Cycles ◽  
Fracturing Experiments ◽  
Cyclic Injection

In hydraulic fracturing applications, there is substantial interest to reduce the formation breakdown pressure. Previous research results show that the cyclic injection method can be used to reduce that pressure. In this study, we conducted laboratory hydraulic fracturing experiments to apply cyclic injection to reduce the breakdown pressures of very tight and strong sandstones. Experimental results show that using cyclic injection the average breakdown pressure was reduced by 18.9% in very tight sandstones and by 7.18% in normal sandstones. This indicates that the effect of cyclic injection is more significant for stronger and tighter rocks. The experiments also reveal that the rock tensile strength plays a more important role in the formation breakdown pressure with a rock strength factor of 2.85. This suggests that the breakdown pressure is higher than expected. In addition, we empirically related the breakdown pressure reduction and the injection pressure amplitude to the number of injection cycles. The curve fitting results imply that the effect of cyclic injection is more important if the number of cycles or the injection pressure amplitude is increased. Based on the results of this research, the in-situ formation breakdown pressure can be reduced by applying the cyclic injection method, and the breakdown pressure reduction is more significant as the number of cycles increases.

scholarly journals Activated Ductile CFRP NSMR Strengthening

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2821
Author(s):  
Jacob Wittrup Schmidt ◽  
Christian Overgaard Christensen ◽  
Per Goltermann ◽  
José Sena-Cruz
Keyword(s):  
Failure Modes ◽  
Elastic Response ◽  
Applied Theory ◽  
Strengthening Effect ◽  
The Novel ◽  
Near Surface ◽  
Linear Elastic ◽  
Near Surface Mounted ◽  
High Elongation ◽  
Strengthened Beam

Significant strengthening of concrete structures can be obtained when using adhesively-bonded carbon fiber-reinforced polymer (CFRP) systems. Challenges related to such strengthening methods are; however, the brittle concrete delamination failure, reduced warning, and the consequent inefficient use of the CFRP. A novel ductile near-surface mounted reinforcement (NSMR) CFRP strengthening system with a high CFRP utilization is introduced in this paper. It is hypothesized that the tailored ductile enclosure wedge (EW) end anchors, in combination with low E-modulus and high elongation adhesive, can provide significant strengthening and ductility control. Five concrete T-beams were strengthened using the novel system with a CFRP rod activation stress of approximately 980 MPa. The beam responses were compared to identical epoxy-bonded NSMR strengthened and un-strengthened beams. The linear elastic response was identical to the epoxy-bonded NSMR strengthened beam. In addition, the average deflection and yielding regimes were improved by 220% and 300% (average values), respectively, with an ultimate capacity comparable to the epoxy-bonded NSMR strengthened beam. Reproducible and predictable strengthening effect seems obtainable, where a good correlation between the results and applied theory was reached. The brittle failure modes were prevented, where concrete compression failure and frontal overload anchor failure were experienced when failure was initiated.

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