Modeling of Before Closure Zero Slope Pressure Derivative in a Diagnostic Fracture Injection Test DFIT

2022 ◽  
Author(s):  
Guoqing Liu ◽  
Jie Wang ◽  
Christine Ehlig-Economides
Keyword(s):  
Interface Crack ◽  
Radial Flow ◽  
Fracture Propagation ◽  
Friction Loss ◽  
Open Crack ◽  
Large Magnitude ◽  
Injection Test ◽  
Layer Interface ◽  
Diffusive Flow ◽  
Tip Extension

Abstract Recent diagnostic fracture injection test (DFIT) data presented on a Bourdet log-log diagnostic plot showed derivative slope of 0 in the before closure (BC) portion of the DFIT response. Some works qualitatively describe it as radial flow. This behavior has not been quantitatively analyzed, modeled and matched. The present work disagrees with the hypothesis of radial flow and successfully matches the relatively flat trend in the Bourdet derivative with a model dominated by friction dissipation coupled with tip extension. The flat trend in Bourdet derivative occurs shortly after shut-in during the before closure period. Because a flat derivative trend suggests diffusive radial flow, our first approach was to consider the possibility that an open crack at a layer interface stopped the fracture propagation and caused the apparent radial flow behavior observed in falloff data. However, a model that coupled pressure falloff from diffusive flow into a layer interface crack with pressure falloff from closure of a fracture that propagated up to the layer interface failed to reproduce the observed response. Subsequently, we discovered that existing models could match the data without considering the layer interface crack. We found that data processing is very important to what is observed in derivative trends and can mislead the behavior diagnosis. We succeeded to match one field DFIT case showing an obvious early flat trend. The presence and dominance of geomechanics, coupled with diffusive flow, disqualify the description of the flat trend in Bourdet derivative as radial flow. Instead, flow friction coupled with tip extension can completely match the observed behavior. Based on our model, cases with a long flat trend have large magnitude near-wellbore tortuosity friction loss and relatively long tip extension distance. Further, we match the near wellbore tortuosity behavior with rate raised to a power lower than the usually assumed 0.5. The significance of these analyses relates to two key factors. First, large magnitude near wellbore tortuosity friction loss increases the pressure required for fracture propagation during pumping. Second, tip extension is a way to dissipate high pumping pressure when very low formation permeability impedes leakoff. Matching transient behavior subject to the presence of both of these factors requires lowering the near-wellbore tortuosity exponent.

Simulation of Hydraulical Fracture Height by Creating Artificial Barrier

2013 ◽  
Vol 734-737 ◽  
pp. 1262-1267
Author(s):  
Chuan Min Li ◽  
Yong Quan Hu
Keyword(s):  
Stress Gradient ◽  
Fracture Propagation ◽  
Propagation Model ◽  
Open Crack ◽  
Fracture Criteria ◽  
Intensity Factors ◽  
Net Pressure ◽  
Fracture Height ◽  
Barrier Zone ◽  
Treatment Pressure

It is quite difficult for reservoir exploitation with worse barrier zone, especially in thin pay-zone, limiting hydraulic fracture height propagation. This paper described the theory of controlling the fracture height by creating artificial barrier, and net pressure distribution in the crack was determined by assuming the artificial barrier is with stress gradient. Then, stress intensity factors in the crack tip were gotten on the basis of fracture mechanics theory, and fracture propagation model was established in accordance with fracture criteria of tensile open crack. The established model also described the action of treatment pressure on the fracture height and influence of artificial barrier on the fracture height propagation. By contrasting the results, it is feasible for artificial barrier to limit the fracture height propagation, and this model also can be used in hydraulic fracturing design in the oilfield.

Interface Crack Between Two Dissimilar Half Spaces Subjected to a Uniform Heat Flow at Infinity—Open Crack

1990 ◽  
Vol 57 (2) ◽  
pp. 359-364 ◽  
Author(s):  
An-Yu Kuo
Keyword(s):  
Thermal Stress ◽  
Stress Intensity ◽  
Temperature Distribution ◽  
Heat Flow ◽  
Interface Crack ◽  
Stress Intensity Factors ◽  
Crack Surface ◽  
Open Crack ◽  
Intensity Factors ◽  
Uniform Heat

The thermal stress problem of an “open” crack situated at the interface of two bonded, dissimilar, semi-infinite solids subjected to a uniform heat flow is studied. Heat transmission between adjacent crack surfaces is assumed to be proportional to the temperature difference between the crack surfaces with a proportional constant h, which is defined as the contact coefficient or interface conductance. Temperature distribution of the problem is obtained by superimposing the temperature field for a perfectly bonded composite solid and the temperature fields for a series of distributed thermal dipoles at the crack location. The distribution function of the dipoles is obtained by solving a singular Fredholm integral equation. Stresses are then expressed in terms of a thermoelastic potential, corresponding to the temperature distribution, and two Muskhelishvili stress functions. Stress intensity factors are calculated by solving a Hilbert arc problem, which results from the crack surface boundary conditions and the continuity conditions at the bonded interface. Thermal stress intensity factors are found to depend upon an additional independent parameter, the Biot number λ = (ah/k), on the crack surface, where a is half crack length and k is thermal conductivity. Dipole distribution and stress intensity factors for two example composite solids, Cu/Al and Ti/Al2O3, are calculated and plotted as functions of λ. Magnitude of the required mechanical loads to keep the interface crack open is also estimated.

The Interface Crack

1977 ◽  
Vol 44 (4) ◽  
pp. 631-636 ◽  
Author(s):  
Maria Comninou
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Interface Crack ◽  
Singular Integral ◽  
Singular Integral Equations ◽  
Open Crack ◽  
Intensity Factors ◽  
Frictionless Contact ◽  
Crack Faces

It is known that oscillatory singularities appear in problems involving interface cracks that are assumed to have open tips. An unsatisfactory aspect of the oscillatory singularities is that they lead to overlapping of the crack faces. The interface crack in a tension field, originally treated by England among others, is thus reconsidered on the basis that the crack is not completely open and that its faces are in frictionless contact near the tips. The formulation leads to a pair of coupled singular integral equations. The singularities, no longer oscillatory, exhibit some unusual features and indicate that the spreading of the interface crack in a tension field is intimately connected with failure in shear. A new stress-intensity factor is obtained and compared to the stress-intensity factors for the completely open crack.

Development of Cu/Insulation Layer Interface Crack Extension Simulation with Crystal Plasticity

2013 ◽  
Vol 52 (4S) ◽  
pp. 04CB05 ◽  
Author(s):  
Kozo Koiwa ◽  
Masaki Omiya ◽  
Nobuyuki Shishido ◽  
Shoji Kamiya ◽  
Hisashi Sato ◽  
...  
Keyword(s):  
Interface Crack ◽  
Crystal Plasticity ◽  
Crack Extension ◽  
Insulation Layer ◽  
Layer Interface

Pre-Frac Injection Test Analysis: A Unified Approach to the Application of Conventional Techniques in an Unconventional Play

2015 ◽  
Author(s):  
P.. Smith ◽  
E.. Pinto
Keyword(s):  
Radial Flow ◽  
Field Tests ◽  
Design Parameters ◽  
Reservoir Pressure ◽  
Unified Approach ◽  
Test Analysis ◽  
Type Curves ◽  
Injection Test ◽  
Test Execution ◽  
Diagnostic Plot

Abstract Pre-fracture injection tests have been commonly used, across the industry, in order to estimate the required hydraulic fracture design parameters and associated reservoir pressure. However, evidence would suggest that industry approaches to both the injection execution and the post-injection analyses are not as equally consistent. The result could potentially be an erroneous and inaccurate interpretation, which could lead to over estimation of these reservoir characteristics and subsequent inefficient fracture design and placement. This paper demonstrates how a unified approach to the analysis of pre-frac injection tests can lead to the valid application of this technique in obtaining reliable estimates of both the reservoir pressure and the matrix permeability in a tight unconventional shale play (Utica play fairway). Analyses of the pressure fall off data, from pre-frac injection tests that were performed in a number of wells, will be discussed here. These analyses included the use of a conventional log-log diagnostic plot, as well as Pressure Decline Analysis using the SQRT (square root time), G function and G dP/dG plots. Finally, the results were also interpreted utilizing the ACA (after closure analysis) approach by employing type curves and flow regime time functions. The results of the formation permeability, the initial reservoir pressure, the closure time and the closure pressure from three of these field tests will be presented in this paper. Two of these tests achieved pseudo-radial flow, whilst one test failed to reach either pseudo-linear or pseudo-radial flow, resulting in a demonstrable overestimation of the reservoir parameters. The paper will present the injection test execution and analysis, as well as confirming the importance of achieving pseudo radial flow in order to obtain reliable and consistent test results.

Heat Transfer and Friction Loss in Laminar Radial Flows through Rotating Annular Disks

1981 ◽  
Vol 103 (2) ◽  
pp. 212-217 ◽  
Author(s):  
S. Mochizuki ◽  
Wen-Jei Yang
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Pressure Drop ◽  
Rotational Speed ◽  
Heat Transfer Performance ◽  
Radial Flow ◽  
Friction Loss ◽  
Transfer Performance ◽  
Flow Through ◽  
Annular Disks

Heat transfer and pressure drop performance are experimentally studied for laminar radial flow through a stack of corotating annular disks. The disk surfaces are heated by condensing steam to create constant surface temperature condition. The traditionally defined friction factor is modified to include the effect of centrifugal force induced by the rotation of the heat transfer surface on core pressure drop. Empirical equations are derived for the heat transfer and friction factors at zero rotational speed. Test results are obtained for various rotational speeds. It is disclosed that (1) The transition in the radial flow through rotating parallel disk passages occurs at the Reynolds number (based on the hydraulic diameter of the flow passage) of 3000 at which stall propagation occurs in the rotor. (2) In the laminar flow regime, its heat transfer performance at zero rotational speed is superior to forced convection in the triangular, square, annular, rectangular and parallel-plane geometries. (3) The effects of disk surface rotation are twofold: a significant augmentation in heat transfer accompanied by a very substantial reduction in friction loss. (4) These rotational effects decrease with an increase in the fluid flow rate until the transition Reynolds number where the effects of centrifugal and Coriolis forces diminish is reached. (5) Heat transfer performance at low through flows is superior to that of high-performance surfaces for compact heat exchangers.

ON THE INTERFACE CRACK MODELS

1988 ◽  
Vol 49 (C5) ◽  
pp. C5-539-C5-544
Author(s):  
T. SUGA ◽  
S. SCHMAUDER ◽  
G. ELSSNER
Keyword(s):  
Interface Crack

Analysis of the Rotor-Stator Interaction in a Radial Flow Pump

2009 ◽  
pp. 141-151 ◽  
Author(s):  
G. Cavazzini ◽  
G. Pavesi ◽  
G. Ardizzon ◽  
P. Dupont ◽  
S. Coudert ◽  
...  
Keyword(s):  
Radial Flow ◽  
Rotor Stator Interaction ◽  
Radial Flow Pump ◽  
Flow Pump
Sign in / Sign up

Export Citation Format

Share Document