Hydraulic Fracture Stimulation Design Considerations and Production Analysis

Abstract

When the word "shale" is included in the name of a formation, a high-rate water frac is often instantly assumed to be the correct choice for hydraulic fracture treatment. This is because high-rate water fracs are the common treatment in the Barnett shale in northeast Texas, and that is the shale reservoir with which industry professionals are most familiar. When a new shale development, such as the Eagle Ford shale in south Texas, is discovered, engineering tends to take a back seat, and a high-rate water frac is often the initial treatment design chosen simply because that is what has been done in the Barnett. Reservoir understanding acquired from core analysis, geomechanical tests, formation evaluation, proppant-embedment testing, stress analysis, and other data are sometimes ignored in the design process.This paper discusses the thought process that engineers are encouraged to follow when deciding what type of completion should be used to fracture stimulate a shale reservoir (water frac, hybrid, or conventional). Considerations, such as the type of hydrocarbon that is expected to be produced, fracture complexity of the reservoir, lithology and mineralogy of the rock, and other reservoir parameters, should be included as part of the completion design. To close the loop, the production also should be evaluated to make good engineering-design changes as the asset is developed. Quantifiable analysis of a stimulation treatment in a horizontal well can be a daunting task because of the complexity and lack of data. Production analyses for several stimulated wells are presented. This application can be directed toward any horizontal completion in low/ultra-low permeability reservoirs and can be performed in a timely manner. The immediate goal of this process is to determine a qualitative measurement of stimulation effectiveness; the eventual goal is a quantitative tool.

The Exploration and Recognition of Stimulated Reservoir Volume for Shale Gas in Sichuan Basin - Taking Well W201 as an Example

“…④ The monitoring results show that complex fracture network appeared after fracturing (shown in the Figure 2), and the expected production is about 1,000m 3 after SRV to this laminate with 5.4× 10 6 m 3 . This well area has the good condition for reconstruction.…”

Evaluating First Eagle Ford Shale Gas Well—Case History from Northern Mexico

“…• Multiple fluid system types are usually necessary in the Eagle Ford shale. Descriptions of fluid systems, such as water frac, conventional frac, and hybrid frac, might not be well-defined or standardized in the industry (Stegent et al 2011), but each one can be applied, depending on the well and formation requirements. • A proper wellbore exit design is necessary to achieve designed rate early in the treatment.…”

“…• Conductivity damage mechanisms, such as proppant embedment, formation fines, crushed proppant, and proppant diagenesis, may also have a great impact on sustaining conductivity with time. • Perf-and-plug completions should consider the use of acid-soluble cement (Stegent et al 2011) in the lateral sections to minimize tortuosity and assist in completion efficiency. • More production history data could help to better understand the reservoir and production performance versus nearby wells.…”

Impact of Rock Mechanics and Formation Softening Analysis in Shale Fracturing Fluid Design

“…The BHN is measured again, and the post-to pre-BHN ratio is observed. Stegent et al (2011) describe how the BHN varies for different shale plays. Some shale plays are softer than others, and vice versa.…”