Compositional Grading in the Ghawar Khuff Reservoirs

Temeng, K.O.; Al-Sadeg, M.J.; Al-Mulhim, Waleed

doi:10.2118/49270-ms

Cited by 35 publications

(11 citation statements)

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“…These are also the first reports of their kind in the literature to the best of our knowledge. Previously, Temeng et al 8 reported a heptane-plus decrease with depth in a hydrocarbon formation in Saudi Arabia without conclusive evidence. Our measurements both in the formation and in the wells (which are connected) confirm the existence of a dense fluid mixture floating on the top of a light fluid mixture.…”

Section: Introductionmentioning

confidence: 95%

Interpretation of the Unusual Fluid Distribution in the Yufutsu Gas-Condensate Field

2003

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It is generally believed that at steady state, a heavy fluid mixture cannot float, without motion, at the top of a light fluid mixture in a cavity. The expectation is that because of pressure diffusion, segregation occurs with the light fluid at the top and the heavy fluid at the bottom. We present, for the first time, an extensive set of measurements in 5-km vertical wells in a large hydrocarbon formation of 1-km thickness with horizontal dimensions on the order of several kilometers that show a high-density fluid mixture at the top of a light-density fluid mixture at steady state. The data in the 5-km wells show liquid in the middle, and vapor at the top and bottom. In the hydrocarbon formation, there is a gradual decrease of density with depth.A theoretical model based on the thermodynamics of irreversible processes is used to provide an interpretation of the unusual density variation vs. depth both in the hydrocarbon formation and in the long wells, as well as the unusual species distribution in the hydrocarbon formation. The results reveal that thermal diffusion (caused by geothermal temperature gradient) causes the segregation of heavy components in the subsurface fluid mixture to the cold side in the Earth (that is, the top), overriding pressure and molecular diffusion (Fickian diffusion). As a consequence of the competition of these three diffusion effects, a heavy fluid mixture can float at the top with a light fluid mixture underneath. In the past, thermal diffusion has been thought of as a second-order effect. For the fluid mixture in our work, thermal diffusion is the main phenomenon affecting the spatial density and species distribution.

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Section: Introductionmentioning

confidence: 95%

Interpretation of the Unusual Fluid Distribution in the Yufutsu Gas-Condensate Field

2003

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“…H 2 S is believed being generated by thermo-chemical sulfate reduction reaction (Temeng et al, 1998). In this process, anhydrite or dissolved sulfate is chemically reduced into H 2 S at the expense of methane and probably hydrocarbons of higher molecular weight (CaSO 4 ϩ CH 4 ¡ CaCO 3 ϩ H 2 S ϩ H 2 O).…”

Section: Introductionmentioning

confidence: 99%

Iron Sulfide and Removal in Scale Formation Sour Gas Wells

et al. 2016

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Scale formation has been a persistent challenge in many sour gas wells producing from one of the world's largest gas reservoir in Saudi Arabia. Accumulation of scale deposits on downhole tubular and in wellhead manifold interferes field operation, limits well accessibility and decreases well productivity. Extensive efforts have been devoted to understand the scale formation process and to develop cost-effective mitigation strategy. This paper discusses the up-to-date knowledge on the scale formation in these prolific gas wells and presents the descaling technologies deployed and currently considered.Scale composition analyses have been performed for a large number of deposits collected during well workovers and interventions. Wide range of mineral phases were identified and their distribution showed significant variations with samples. Scale often consisted of several different mineral phases. Iron sulfides were usually the dominant components, these included pyrrhotite, troilite, mackinawite, pyrite, marcasite and greigite. Ferric iron scales, such as hematite, magnetite, akaganeite, goethite and lepidocrocite, were also common in the scale mixtures. Common mineral scales, especially calcite, were often found. In addition, iron carbonate and other ferrous iron compounds were also identified. The relative abundance of these minerals showed wide-ranging variations from well to wells. Those variations also changed and with depth and time in the given wells. A more interesting phenomenon was the layered structure in the scale deposits, with two distinct layers having very different compositions. These results provided critical information for the understanding of scaling formation process.Scale removal with chemical method had limited success in past. Scale dissolvers, based on HCl acid, caused severe tubular corrosion and formation damage. Different mechanical techniques have been tested and implemented over the years. These field experiences are reviewed in the paper. Also, challenges and requirements for scale dissolvers are discussed.

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“…3 The non-associated gas is sour with hydrogen sulfide content that varies from 0 to 10 mol%. 4 Wells that produce sour gas with high levels of hydrogen sulfide are completed with low-carbon steel tubulars (L-80 and C-95). To enhance the productivity of these wells both matrix acidizing and acid fracturing treatments were used.…”

Section: Introductionmentioning

confidence: 99%

“…This acid system is also based on HCl/formic and contains a synthetic polymer, a cross-linker, and a breaker, and other acid additives. This acid cross-links over a narrow pH range (2)(3)(4) where its viscosity increases by several order of magnitude. The objectives of this work were to: (1) Determine the advantages of using insitu gelled HCl/formic acid over gelled HCL/formic acid (2) Evaluate field application of in-situ gelled acids to stimulate deep carbonate gas reservoirs, and (3) Optimize the treatment based on lab and field results.…”

Section: Introductionmentioning

confidence: 99%

Long-Term Comparative Evaluation of HCl/Formic Acid System Used To Stimulate Carbonate Formations at Severe Conditions in Saudi Arabia

et al. 2006

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TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThe high levels of carbon dioxide and low levels of hydrogen sulfide content of some deep and high temperature gas producers contributed in the requirement to complete these wells using super Cr-13 tubings. Due to the low permeability of the formation and the associated formation damage issues, acid fracturing treatments were required to optimize the productivity of these wells. This paper describes the selection, optimization and long term comparative evaluation of the gelled and in-situ crosslinked HCl/formic acid systems used this type of wells. The high temperatures encountered in deep wells and the susceptibility of super Cr-13 to severe corrosion in high concentration HCl systems used for stimulation purposes added one additional difficulty to the acid stimulation process. To overcome these problems, extensive experimental and field studies were performed to select an acid system to enhance the productivity of these wells.Core flood tests performed with HCl/formic acid systems showed their ability to create deep wormholes in tight carbonate cores; however the corrosiveness of these systems at downhole conditions could be severe if the correct type and concentration of corrosion inhibitor is not used. In general, for the HCl/formic acid systems at downhole conditions (275°F) it was found that high concentrations of corrosion inhibitors are required to protect the super Cr-13 completions.Based on lab tests study acid stimulations were performed, the flow back fluid was recovered and analyzed to observe the corrosion problems and to optimize the corrosion inhibitor.In all the cases the wells responded very well to the acid stimulation and the completion integrity was not compromised in a short or long term. The paper also shows for the first time a comparative long term well response to the acid stimulation of the two acid systems used in the area, showing the better performance of the in-situ crosslinked HCl/formic system over the gelled HCl/formic system.

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Compositional Grading in the Ghawar Khuff Reservoirs

Cited by 35 publications

References 0 publications

Interpretation of the Unusual Fluid Distribution in the Yufutsu Gas-Condensate Field

Interpretation of the Unusual Fluid Distribution in the Yufutsu Gas-Condensate Field

Iron Sulfide and Removal in Scale Formation Sour Gas Wells

Long-Term Comparative Evaluation of HCl/Formic Acid System Used To Stimulate Carbonate Formations at Severe Conditions in Saudi Arabia

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