1. Recent Advances in Oil and Gas Production Engineering
Cai Wenbin
School of Petroleum Engineering
Xi’an Shiyou University

2. Course Contents: Chapter 1 Introduction
Chapter 2 Gas Well Unloading Technologies
Chapter 3 Advanced Hydraulic Fracturing Technologies
Chapter 4 Horizontal Well Fracturing
Chapter 5 Coiled Tubing Operations and Intelligent Well
Chapter 6 Unconventional Oil and Gas Production
Chapter 7 Shale Gas Development

3. Chapter 7 Shale Gas Development
7.1 Shale Gas Introduction
7.2 Geology Aspects for Production
7.3 Reservoir Aspects for Production
7.4 Stimulation Technologies
7.5 Simultaneous Fracturing
7.6 Case Study of Shale Gas Production

4. Chapter 7 Shale Gas Development
Shale gas is natural gas that is found trapped within shale formations. Shale gas has become an increasingly important source of natural gas in the United States since the start of this century.

5. Chapter 7 Shale Gas Development
Shale gas is a kind of unconventional sources of natural gas; like coalbed methane, tight sandstones. There are two critical shale gas technology------hydraulic fracturing and horizontal drilling

6. Chapter 7 Shale Gas Development
## Shale gas is natural gas produced from shale formations that typically function as both the reservoir and the source rocks for the natural gas.
## In terms of chemical makeup, shale gas is typically a dry gas composed primarily of methane (60~95% v/v), but some formations do produce wet gas.
## Gas shale formations are organic-rich shale formations that were previously regarded only as source rocks and seals for gas accumulating in the strata near sandstone and carbonate reservoirs of traditional onshore gas development.

7. Shale Samples of Different Plays in U.S.
Chapter 7 Shale Gas Development
Shale Samples of Different Plays in U.S.

8. Mineral Compositions of Different Shale Rock
Chapter 7 Shale Gas Development
Mineral Compositions of Different Shale Rock

9. Chapter 7 Shale Gas Development
Shale gas is the hydrocarbon gas present in organic rich, fine grained, sedimentary rocks (shale and associated lithofacies). The gas is generated and stored in situ in gas shale as both sorbed gas (on organic matter) and free gas (in fractures or pores). As such, shale containing gas is a self-sourced reservoir.
Low-permeable shale requires extensive fractures (natural or induced) to produce commercial quantities of gas.

10. China (Sichuan and Tarim Basins)
Chapter 7 Shale Gas Development
China (Sichuan and Tarim Basins)
In 2011, China was estimated to have 1275 trillion cubic feet of technically recoverable shale gas.
Since then a government geological survey confirmed a total of 882 trillion cubic feet of technically recoverable shale gas, excluding Tibet.
The Sichuan Basin, located in south central China, accounts for 40% of the country's shale resources.

11. Major Shale Basins in 32 countries
Chapter 7 Shale Gas Development
Major Shale Basins in 32 countries

12. Shale Gas Plays Throughout the Country of U.S
Chapter 7 Shale Gas Development
Shale Gas Plays Throughout the Country of U.S

13. Chapter 7 Shale Gas Development
A study from Manchester University conclued that, compared with coal, conventional and liquefied gas, nuclear, and solar
Shale gas worse than coal for three impacts and better than renewables for four.
It has higher photochemical smog and toxic land than the other options.
Shale gas is a sound environmental option only if accompanied by stright regulation.

14. Chapter 7 Shale Gas Development
One of the byproducts of shale gas exploration is the shale oil production. By 2035, shale oil production could "boost the world economy ”by up to $2.7 trillion. It has the potential to reach up to 12 percent of the world’s total oil production — “revolutionizing” the global energy markets over the next few decades."

15. Chapter 7 Shale Gas Development
Some analysts expect that shale gas will greatly expand worldwide energy supply. China is estimated to have the world's largest shale gas reserves. A study concluded that increased shale gas production in the US and Canada could help prevent Russia and Persian Gulf countries from dictating higher prices for the gas they export to European countries.

16. Chapter 7 Shale Gas Development
7.1 Shale Gas Introduction
7.2 Geology Aspects for Production
7.3 Reservoir Aspects for Production
7.4 Stimulation Technologies
7.5 Simultaneous Fracturing
7.6 Case Study of Shale Gas Production

17. Chapter 7 Shale Gas Development

18. Chapter 7 Shale Gas Development
Horizontal drilling and hydraulic fracturing revolutionized drilling technology and paved the way for developing several giant natural gas fields.
These include the Marcellus shale in the Appalachians, the Haynesville shale in Louisiana, and the Fayetteville shale in Arkansas.
These enormous shale reservoirs hold enough natural gas to serve all of the United States' needs for 20 years or more.

19. Chapter 7 Shale Gas Development
Hydraulic properties are characteristics of a rock such as permeability and porosity that reflect its ability to hold and transmit fluids such as water, oil, or natural gas.
In this respect, shale has a very small particle size so the interstitial spaces are very small. In fact they are so small that oil, natural gas, and water have difficulty moving through the rock.
Shale can therefore serve as a cap rock for oil and natural gas traps and it also is an aquiclude that blocks or limits the flow of underground water.

20. Chapter 7 Shale Gas Development
7.1 Shale Gas Introduction
7.2 Geology Aspects for Production
7.3 Reservoir Aspects for Production
7.4 Stimulation Technologies
7.5 Simultaneous Fracturing
7.6 Case Study of Shale Gas Production

21. Schematic Geology of Natural Gas Resources
Chapter 7 Shale Gas Development
Schematic Geology of Natural Gas Resources

22. Chapter 7 Shale Gas Development
both biogenic and thermogenic shale gases remain where they were first generated and can be found in three forms:
Free gas in the pore spaces and fractures;
Adsorbed gas, where the gas is electrically stuck to the organic matter and clay; and
A small amount of issolved gas that is dissolved in the organic matter.

23. Chapter 7 Shale Gas Development
Four properties that are important characteristics in each shale gas play are:
the maturity of the organic matter
the type of gas generated and stored in the reservoir-biogenic gas or thermogenic gas
(iii) the total organic carbon (TOC) content of the strata
(iv) the permeability of the reservoir

24. Chapter 7 Shale Gas Development
7.1 Shale Gas Introduction
7.2 Geology Aspects for Production
7.3 Reservoir Aspects for Production
7.4 Stimulation Technologies
7.5 Simultaneous Fracturing
7.6 Case Study of Shale Gas Production

25. Chapter 7 Shale Gas Development
Shale has low matrix permeability, so gas production in commercial quantities requires fractures to provide permeability. The shale gas boom in recent years has been due to hydraulic fracturing to create extensive artificial fractures around well bores.

26. Chapter 7 Shale Gas Development
Horizontal Well and Hydraulic Fracturing

27. Chapter 7 Shale Gas Development
Pad Drilling

28. Chapter 7 Shale Gas Development
Horizontal drilling is often used with shale gas wells, with lengths up to feet in the shale, to create maximum borehole surface area in contact with the shale.

29. Multilateral Drilling
Chapter 7 Shale Gas Development
Multilateral Drilling

30. Chapter 7 Shale Gas Development
7.1 Shale Gas Introduction
7.2 Geology Aspects for Production
7.3 Reservoir Aspects for Production
7.4 Stimulation Technologies
7.5 Simultaneous Fracturing
7.6 Case Study of Shale Gas Production

31. Chapter 7 Shale Gas Development
Large-volume slick water fracture stimulation has proven very successful in naturally fractured shale reservoirs such as the Barnett Shale of North Texas, the Fayetteville Shale in Arkansas, the Marcellus Shale in Appalachia Basin, and many other shale reservoirs.
These shales require hydraulic fracture stimulation in order to obtain commercial production.
The characteristics and mineralogical properties of the shale allow for the creation of complex fracture geometries that contact large surface areas during fracture stimulation, which all contribute to production.

32. Chapter 7 Shale Gas Development
Hydraulic fractures created during treatments in these shales cannot beconsidered the same as conventional fractures in that typical two-wing fracture geometry does not occur.
The fracture characterization is much more complex, as has been evidenced through utilization of microseismic technology to “fracture map” the stimulation treatments.
The result of microseismic mapping has shown that fracture stimulation in the Barnett can create a fracture “fairway” with broad extent and length with multiple fracture orientations.

33. Chapter 7 Shale Gas Development
It is therefore an object of this invention to locally alter in-situ stress conditions and control the direction that simultaneous hydraulic fracture will propagate.
It is another object of this invention to locally alter in-situ stress conditions and generate simultaneous hydraulic fractures which will cut into a natural fracture system and connect at least one fracture to the wellbore.
It is yet another object of this invention to increase hydrocarbon production froma subsurface hydrocarbon-bearing formation via simultaneous hydraulic fracturing from at least two wellbores.
It is still yet a further object of this invention to obtain more effective hydraulic fracturing results under different subsurface in-situ stress conditions.

34. Shale Gas Plays in the Unites States
Chapter 7 Shale Gas Development
Shale Gas Plays in the Unites States

35. Chapter 7 Shale Gas Development
As we can see, in 2012, only the US, Canada, and China produce shale gas in commercial quantities, and only the US and Canada have significant shale gas production.

36. Chapter 7 Shale Gas Development

37. Chapter 7 Shale Gas Development
Newark East (Barnett Shale) daily production by date. Production is divided by year of first production. Note reverse production decline since 1999 for wells first put on production before This reverse is a result of reworks and re-fracs of these older wells. Data from Texas Railroad Commission

38. Chapter 7 Shale Gas Development
Annual gas production from several U.S. shale plays. Barnett data for 2002 is calculated by doubling production for the first half of the year (which is 97 BCF, for a conservative year-end estimate of 194 BCF). (After Hill and Nelson, 2000.) Barnett production data for the first six months of 2002 is from the Texas Railroad Commission.

39. Chapter 7 Shale Gas Development
Reference
[1] Speight J G. Shale gas production processes[M]. Gulf Professional Publishing, 2013.
[2] Arthur J D, Langhus B, Alleman D. An overview of modern shale gas
development in the United States[J]. All Consulting, 2008, 3:
[3] Gadonneix P, de Castro F B, de Medeiros N F, et al. Survey of Energy Resources: Focus on Shale Gas[J]
[4] Schein G W, Weiss S. Simultaneous fracturing takes off[J]. Hart's E & P, 2008, 81(3):
[5] Bowker K A. Development of the Barnett Shale Play, Fort Worth Basin[J]. AAPG Bulletin, 2007, 91(4).

40. Chapter 6 Unconventional Oil and Gas Production
Tea Break… 40