Single Point of Initiation, Dual-Fracture Placement for Maximizing Well Production

2010

All Days

In the oilfield, the term "unconventional" almost always means difficult to get, for one or another reason. One reason addressed in this paper relates to formations characterized by the lack of permeable features that connect or can be easily connected to the wellbore using conventional stimulation techniques. The common logic of placing larger and larger fractures does work but, when using this approach, the cost-over-reward ratio can be far from desirable.It is well-known that placing a second fracture sometime later in the life of a well will result in a fracture that extends in a slightly different direction, mostly caused by the drainage of the fluid near the fracture face. In this situation, fracture redirection is probably caused by the pore-pressure decline near the producing fracture face. In some instances, the new fracture produces almost as if it has reached a new formation.This paper discusses placement of such "second" (or third) hydraulic fractures within the same time domain from the same wellbore section. It is believed that the first fracture will modify the stress field to a perpendicular direction. Combined with the hypothesis of the hard-to-accept concept that fractures often shy away from the most productive areas, this approach will cause the second fracture to extend directly into the more productive areas, thus providing a substantial production boost.

Section: The Art Of Fracture-direction Modificationmentioning

confidence: 80%

Multioriented Fracturing in Unconventional Reservoirs Offers Improved Production by Better Connectivity

2010

All Days

“…Using this type of system, windows can be opened or closed in any sequence as prescribed. The process takes advantage of two phenomena: the altered stresses that can occur when a nearby fracture is opened (Warpinski et al 1989, Surjaatmadja 2007a, 2007b, 2007c2008;Moschovidis et al 2000) and the creation of slip planes by the naturally varying widths of each fracture forming the horizontal microfractures, as illustrated in Fig. 7 (Surjaatmadja 2010).…”

Section: Asf Methodsmentioning

confidence: 99%

Efficient Coiled-Tubing Fracturing for Proppant-Placement Assurance and Contingency-Cost Mitigation

East

2012

All Days

Self Cite

Combining production from multiple intervals within a well during completion has been used for many years. Many of these reservoirs required hydraulic-fracture stimulation, and a number of promising fracturing methods have been developed where several stages can be performed sequentially, provided there is some method used to isolate previously stimulated intervals.One method claims high efficiency by using high-rate treatments and limited-entry perforating concepts. However, the promises proved to be elusive. Contingencies for early screenout, perforating gun missfires, and other equipment failures have often dramatically impacted completion efficiency. To guard against these failures, the proppant schedules were underdesigned or purposely overflushed, thus reducing the resulting fracture conductivity.To achieve limited-entry diversion, high-treatment rates were used, which required a large amount of hydraulic horsepower onsite. Yet, even when efficiencies were achievable, production logging often showed that, at best, only 50% of the intended fracturing targets would actually produce at fracture-stimulated rates. Discovery of an important phenomenon was recently explained using computational fluid dynamics (CFD) simulation. It was found that the difference in the physical qualities of proppant and the carrying fluid cause the upper intervals to receive mostly proppant-free fluid.Pinpoint-stimulation fracturing methods can allow all of the multiple intervals completed to be stimulated efficiently, such that all intervals received the designed proppant volumes one interval at a time. For the most effective of these methods, coiled tubing (CT) is used to hydrajet perforate intervals for individual fracturing treatments, and proppant plugs are used to isolate stimulated intervals while maximizing near-wellbore (NWB) conductivity. These methods do not require removing the CT from the well between treatments, so early screenouts can be remediated immediately with minimal impact.A new entry in this class of fracturing that allows real-time, on-demand downhole proppant-schedule control can be combined with real-time fracture-mapping diagnostics to optimize stimulated reservoir volume (SRV) on-the-fly, when needed. A 15-stage completion in the Marcellus is used to demonstrate the process.

“…As such, formations were generally near the surface. It was quite common for hydrocarbons to be discovered at depths less than 4,000 ft, and performing simple fracture stimulations was usually sufficient to obtain acceptable production (Surjaatmadja 2007a(Surjaatmadja , 2007b(Surjaatmadja , 2007c(Surjaatmadja , 2008(Surjaatmadja , 2010Lewis and Surjaatmadja 2015). However, as shallow formations became less productive and deeper formations were explored, finding new producing areas in a known producing formation could be described as Љhit and missЉ (Surjaatmadja et al 2003), meaning that luck was often a factor.…”

Section: Modifying the Direction Of Maximum Stressmentioning

confidence: 99%

“…Surjaatmadja suggests that the missing factor in these studies was time (Surjaatmadja 2007a(Surjaatmadja , 2007b(Surjaatmadja , 2007c(Surjaatmadja , 2008) (e.g., the dynamics of the rock movement process). He argues that the behavior of formation rock can be conveniently modeled as a Couette interaction between rock layers (or, in Couette's terms, Љflow linesЉ); hence, the behavior of the rock during a fracture opening process can be represented by a very viscous media, such as plastic models.…”

Section: Introductionmentioning

confidence: 97%

A Novel Hydraulic Fracturing Technique Greatly Improves Hydrocarbon Recovery Through the Use of Temporary Beneficial Changes in Stress Anisotropy

SPE/IATMI Asia Pacific Oil &Amp; Gas Conference and Exhibition

Lewis

2015

Self Cite

The effects of the earth's tectonic movements are well understood, especially in the formulation of stress anisotropy in a large region. This primarily mechanical effect stays unchanged because the support systems, such as faults, compressions, etc., remain unchanged until the next major tectonic activity. On the other hand, pressure effects are generally semi-permanent and are usually affected by the production history of the formation. In this stress domain, fracture placement during a stimulation treatment will always follow the direction of maximum stress; by definition, this is a fixed direction defined by the known stress anisotropy landscape. This paper presents a different approach for the stimulation process. Instead of a conventional, static, or end-point vision of the stimulation, a dynamic, or temporary, time-dependent stimulation method is introduced. The new method creates a small tectonic motion-significantly smaller than that of natural tectonics-and uses it to temporarily modify the local stress anisotropy. The ЉmicroЉ tectonic motion is created by means of a conventional fracture placed in the natural maximum stress direction. Another fracture can then be created using the same approach but in a temporarily modified stress field that forces it in a different fracture direction. This new multioriented hydraulic fracture (MOHF) stimulation method can enhance state-of-the-art hydraulic fracturing technology by requiring an understanding of the transient geomechanic response in the treatment area.As a time-dependent method, this approach can create new opportunities in both conventional and unconventional plays by providing connectivity to previously unattainable locations in the formation. Unfortunately, it can also result in new complications. Industry standard fracture simulation technology becomes incomplete, as most models neglect the transient response of the system. Additionally, the availability of data related to the dynamic behavior of rocks is limited. The dynamic compression of the rock, slip characteristics between rock layers, and the amount of energy stored within slip planes-all recorded as a function of time-are particularly important when considering an MOHF process. Additional testing should be performed to obtain these data. With such data, time-sensitive operational recommendations for performing the MOHF stimulation can be provided to help achieve the maximum production increase from the well. This paper also discusses a computational validation of the MOHF process. As traditional hydraulic fracture simulations are derived using static formation properties and steady-state assumptions of the formation behavior, a unique transient three-dimensional (3D) computational geomechanic fracture simulator was developed to perform this study. The new model incorporates cohesive zone elements to represent the fracture plane and captures the dynamics of fracture initiation and propagation, as well as the transient stress modification in the formation. A realistic 3D fracture transient beha...