Advanced Horizontal Well Fracturing
Instructor: Prof. Ali Daneshy
Duration: 2 Days
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This is a down-to-earth, easy to understand nuts and bolts course that presents tools and techniques for creation of multiple fractures in horizontal wells for successfully producing extremely low permeability reservoirs.
Horizontal well fracturing is beset by many perplexities, including very high initial treatment pressures even at low injection rates, screen-outs even at very low sand concentrations, very sudden screen-outs in mid treatment, large variances in pressure behavior of different stages in the same well, and large differences in production results from well to well. The catch-all word being used to describe all of these is “complex” fracturing. This course will show that hydraulic fracturing of horizontal wells is NOT “complex” and can be explained by easy-to-understand mechanisms and principles. Furthermore, the course offers tools and techniques for avoiding and overcoming these variances.
Successful fracturing of a horizontal well requires deeper understanding of the relationship between reservoir and formation properties, in-situ stresses, well completion, and details of fracture design. Through numerous case histories and tracer logs the course shows that many horizontal well fractures include a mix of axial (longitudinal) and transverse fractures along the length of the well. The cause of this behavior is traced back to completion techniques and fracture designs. The many case histories covered in this course include active US and Canadian tight reservoirs such as Bakken, Barnett, Cardium, Fayetteville, Granite Wash, Haynesville, Marcellus, Montney, Nordegg, Viking, and more. It presents the different fracturing strategies that are being used in different geologic formations, and the completion options that help their implementation. It also presents several techniques for on-site and post-job analysis of treatment data for continuous improvement of production results.
Important engineering parameters for successful fracturing of horizontal wells include the length of the horizontal well, type of completion (uncemented vs. cemented hole), selection of the specific completion system and its functional reliability during the entire fracturing operations, the number and spacing of the fractures, the type and volume of frac fluid, injection rate, and the type and concentration of proppant. This course offers an in-depth review of the different completion techniques presently used by the industry and the operational strengths and weaknesses of each one of them.
This course is designed specifically for practicing engineers and geologists. It is suited for all interested in improving the outcome of hydraulic fracturing treatments in horizontal wells, including drilling, completion, reservoir and production engineers as well as geologists and geophysicists. Both technical and management staff will benefit from attending this course.
Class Agenda
Day 1
Morning session
Mechanics of fracture initiation
Presentation will show why the natural tendency of fractures in horizontal wells is to initiate axially (longitudinally). Depending on the relative orientation of the wellbore with respect to in-situ principal stresses, these may later re-orient to become perpendicular to the least principal stress. Through several case histories and actual well data, it will be shown that in fact many horizontal well fractures include large axial fracture segments. It will also show how to detect presence of axial fractures from treatment data. Specific completion practices will be recommended to promote initiation of transverse fractures.
Mechanics of fracture extension
Majority of horizontal well fractures grow off-balance. The course will discuss when this is beneficial to production (and how to promote it), and, where and how to discourage off-balance growth. Several case histories are used to illustrate the point.
Afternoon session
Fracturing options in open-hole completions with case histories
Common problems in open holes and recommendations
Presentation will include a comprehensive review and analysis of existing completion practices for fracturing open (uncemented) horizontal wells, with multiple case histories for each case. It will also discuss how these completion systems have fared in real operations
Day 2
Morning session
Fracturing options in cemented cased-hole completions with case histories
Common problems in cased holes and recommendations
This segment includes a comprehensive review of existing completion practices for fracturing cased and cemented horizontal wells, with multiple field examples for each case, including their important advantages and disadvantages.
Afternoon session
Fracturing fluids and proppants This segment presents a discussion of common fluids, proppant, and additives used in horizontal well fracturing, their engineering properties, and applications.
Production strategies: matching fracturing with production objectives
The presentation covers the type of fracture, spacing, size, amount and type of proppant, cost, etc. suitable for different types of formations. The coverage will include carbonates, sandstones and shales, as well as oil and gas.
Production data analysis The observed production profiles of several treatments are analyzed, and simple techniques are offered to match the fracturing strategy with optimum production and the desired cash flow objectives.
Diagnostic Tool The relative value and reliability of various diagnostic tools. These include treatment data, miroseismic, and different types of tracer logs.
Summary and discussion Specific questions from the audience will be discussed in this segment.