Development Update for an Emerging Shale Gas Giant Field—Horn River Basin, British Columbia, Canada

Reynolds, Murray; Munn, Darren Leslie

doi:10.2118/130103-ms

Cited by 26 publications

(7 citation statements)

References 4 publications

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“…Highly reactive Fe 2+ /Fe 3+ ions may participate in production of water insoluble iron hydroxide, goethite, hematite or magnetite according to eqs to : It is worth mentioning that the imbibition experiments are conducted at room temperature, atmospheric pressure, and nearly neutral pH, which are different compared with the reservoir conditions. For example, Horn River reservoir gas contains about 9–14% of CO 2 , and the reaction of CO 2 with water can potentially produce carbonic acid. It must be noted that although carbonic acid production can reduce the pH, natural buffer systems such as dolomite and calcite may neutralize the pH under reservoir conditions .…”

Section: Resultsmentioning

confidence: 99%

Effects of Dissolved Oxygen on Water Imbibition in Gas Shales

Binazadeh

Zolfaghari

et al. 2018

Energy Fuels

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Understanding the water uptake of gas shales is critical for designing and optimizing hydraulic fracturing operations during which a large volume of fracturing water containing dissolved oxygen is injected into tight reservoirs. Recent studies show that the dissolved oxygen may promote oxidation reactions which can affect salinity and pH value of flowback water; however, the effects of dissolved oxygen and oxidation reactions on water imbibition into the shale matrix and on the concentration of individual ions in flowback water are still poorly understood. In this study, we conduct water imbibition experiments under degassed and oxic conditions, and measure the imbibed water mass and concentrations of different ions in water. The results show that the initial rate and final amount of water imbibition are higher under degassed conditions compared with that under oxic conditions. These differences are mainly due to the enhanced dissolution of air in the shale pore network into the imbibing water under degassed conditions and the consequent increase in relative permeability of water. The results also suggest that oxidation of pyrite by dissolved oxygen produces sulfate and iron ions. The abundance of pores in the vicinity of pyrite minerals as observed in the SEM/EDS images provides a pyrite, water, and oxygen rich environment which favors pyrite oxidation.

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Section: Resultsmentioning

confidence: 99%

Effects of Dissolved Oxygen on Water Imbibition in Gas Shales

Binazadeh

Zolfaghari

et al. 2018

Energy Fuels

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“…Recent imbibition studies show that brine and water uptake of several samples from the Horn River Basin , are considerably higher than their oil uptake. However, oil completely spreads on the fresh break of these samples while water does not.…”

Section: Introductionmentioning

confidence: 99%

Advances in Understanding Wettability of Gas Shales

2014

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Recent experiments show the strong water uptake of gas shales which are strongly oil-wet based on contact angle measurements. 1,2 Clay hydration, microfracture induction, lamination, and osmotic effect are collectively responsible for the excess water uptake. However, the previous measurements are not sufficient to isolate the above factors nor to explain why the bulk of shale samples can hardly imbibe the oil which completely spreads on their surface. To answer the remaining questions, we measure and compare spontaneous imbibition of oil and water into the crushed packs of the similar shales. In contrast to the intact samples, the crushed samples consistently imbibe more oil than water. The comparative study suggests that the connected pore network of the intact samples is water wet while the majority of rock including poorly connected pores is oil-wet. This argument is backed by complete spreading of oil on fresh surfaces of the rock. In contrast to the artificial pores of crushed rock, the existing pores of intact rock are already wetted by a film of water and/or covered by precipitated salt, which gives the pores a preference for water over oil. Furthermore, the presence of salt in the pore space provides an additional force for water uptake through an osmotic effect. This argument is backed by the observed reduction in shale alteration and water imbibition through increasing the salt concentration.

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“…Mineralogy of the shale samples is reported in Table . Detailed information regarding this shale play can be found elsewhere. − The average particle size of the powder is confirmed by microscope to be ∼1 μm diameter (Figure a).…”

Section: Methodsmentioning

confidence: 87%

Effect of Electrostatic Interactions on Water Uptake of Gas Shales: The Interplay of Solution Ionic Strength and Electrostatic Double Layer

Binazadeh¹,

Xu²,

Zolfaghari³

et al. 2016

Energy Fuels

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We conduct spontaneous imbibition experiments using different fluids (deionized, DI, water and brines) and different media (unwashed and washed shale powder) to study the wetting behavior of the shale samples from the Horn River Basin (HRB), a massive unconventional gas play in the Western Canadian Sedimentary Basin. As expected, unwashed shale powder imbibes DI water faster than brine. Surprisingly, washing the powders results in faster imbibition of DI water. The imbibition of DI water into washed shale powders, which have a reduced soluble/leachable ion content, cannot be fully explained by osmotic effects. We explain the observed imbibition profiles using the electrostatic interaction theory. We measure the ion concentration of the brines by ICP-MS analysis and determine the ionic strength, I, of the in situ formed brine. We also calculate the characteristic thickness of electrostatic double layer, κ–1, formed around the surface of charged shale powders. The results indicate that the imbibition rate depends on the κ–1value of the in situ formed brine. Electrostatic interaction is part of the disjoining pressure which is not considered in the Young–Laplace equation. A higher κ–1 value enlarges the electrostatic interaction range, which results in formation of a thicker hydration shell around the surface of the shale powder and increases the imbibition rate.

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Development Update for an Emerging Shale Gas Giant Field—Horn River Basin, British Columbia, Canada

Cited by 26 publications

References 4 publications

Effects of Dissolved Oxygen on Water Imbibition in Gas Shales

Effects of Dissolved Oxygen on Water Imbibition in Gas Shales

Advances in Understanding Wettability of Gas Shales

Effect of Electrostatic Interactions on Water Uptake of Gas Shales: The Interplay of Solution Ionic Strength and Electrostatic Double Layer

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