Scanning Electron Microscope Pictures of Reservoir Rocks Reveal Ways to Increase Oil Production

Holub, R.W.; Noel, R.P.; Weinbrandt, R.M.

doi:10.2523/4787-ms

Cited by 3 publications

(5 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Most prior investigations studied formation fines found in consolidated sandstone, but unconsolidated sandstones were selected here because fine particles could be separated easily from larger sand grains for further examination and because the problems associated with fine-particle movement are particularly acute in unconsolidated formations when sand control techniques must be used. Three types of analyses were conducted on these samples: (1) scanning electron microscope (SEM) examinations to determine particle size and shape, (2) sieve analyses to determine the amounts of various sizes of particles present, and (3) X-ray analyses to determine mineralogical content. Fig.…”

Section: Analysis and Description Of Formation Finesmentioning

confidence: 99%

Formation Fines and Factors Controlling Their Movement in Porous Media

Muecke

1979

Journal of Petroleum Technology

355

136

View full text Add to dashboard Cite

Microscopic observations of fine-particle movement in micromodels of porous media have shown that transport of these particles by fluids porous media have shown that transport of these particles by fluids moving through pores is controlled by several factors. Besides mechanical bridging at pore restrictions, fines movement also is influenced strongly by particle wettability and the relative amounts of fluids flowing through the pores when two or more immiscible fluids are present. Introduction Very small particles of loose solid materials are present in the pore spaces of all sandstone reservoirs. These particles, called formation fines, can be incorporated in the particles, called formation fines, can be incorporated in the formation as it is deposited during geologic tune, or they can be introduced into the formation during drilling and completion operations. Regardless of their mode of entry, they long have been recognized to cause severe formation damage. This is because these particles are not held physically in place by the natural cementatious material that binds larger sand grains together, but instead are individual particles located on the interior surfaces of the porous matrix. Thus, these particles are free to migrate through the pores along with any fluids that flow in the reservoir. If these particles do migrate, but are not carried all the way through the formation by produced fluids, they can concentrate at pore restrictions, causing severe plugging and large reductions in permeability.Numerous studies have been conducted to determine the composition, physical characteristics, and other factors controlling the behavior of these materials while the industry has tried to develop techniques for overcoming their undesirable effects. Although these studies have contributed significantly to our understanding of fines and their movement in porous media, there is still considerable need to extend this knowledge if satisfactory remedies for the fines-plugging problems are to be developed. This paper discusses research studies that focused on determining the effects of both single- and multi-phase fluid flow on fine-particle movement in porous media. Most conclusions in this study were reached after observing (through an optical microscope) the movement of particles when carried by various fluids that were injected into a micromodel of porous media. Some experiments also were conducted by flowing fluids through linear sand packs and by monitoring the particle content of the effluent to verify the observations made in the micromodel. Results show that several factors affect particle migration. As has been recognized, mechanical bridging at pore restrictions does occur if certain conditions, such as pore restrictions does occur if certain conditions, such as particle size and concentration, are met. However, this is particle size and concentration, are met. However, this is by no means the only mechanism that is important for controlling fine-particle mobility. When immiscible fluid phases are present in pore spaces, wettability of the phases are present in pore spaces, wettability of the particles and the relative amounts of fluids flowing particles and the relative amounts of fluids flowing through the pores also influence particle movement strongly.The observations made here help explain why the onset of water or gas production can cause fines to move and can lead to well productivity problems, and why injection of seemingly nonreactive fluids (such as water, oil, or solvent/surfactant solutions) often leads to at least temporary removal of near-wellbore damage. JPT P. 144

show abstract

Section: Analysis and Description Of Formation Finesmentioning

confidence: 99%

Formation Fines and Factors Controlling Their Movement in Porous Media

Muecke

1979

Journal of Petroleum Technology

355

136

View full text Add to dashboard Cite

show abstract

“…2 , which is significantly less than the allowable corrosion rate of 0.05 lb/in. 2,16 The amount of dissolved iron can be also used to determine the thickness of mill scale layer. If the thickness of the scale was assumed to be independent of length, then the average scale thickness is 0.000546 inch, Table 3.…”

Section: Flowback Profiles -Case Studies Bullheading Methodsmentioning

confidence: 99%

“…2 , which is significantly less than the allowable corrosion rate of 0.05 lb/in. 2,16 Acid Volume and Flowrate It is evident from the flowback results that the volume of acid used to pickle the tubing was overestimated. However, there were a few examples of pickle design where the acid volume was underestimated.…”

Section: Coiled Tubing Methodsmentioning

confidence: 99%

“…[1][2][3][4][5][6][7][8] The process can be considered as flow in a tube or annulus with heterogeneous chemical reactions occurring at the wall of the tube. 9,10 From well stimulation point of view, the purpose of the tubing pickle treatment is to clean the production tubing from any damaging material prior to conducting the main stimulation treatment.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Tube Pickling Procedures: Case Studies

Al-Mutairi

Nasr‐El‐Din

2005

Proceedings of SPE European Formation Damage Conference

View full text Add to dashboard Cite

Tubing pickle treatments can eliminate formation damage that is caused by introducing millscale, pipe dope and other tubular contaminants into the formation. Two of acid pumping techniques implemented to perform the pickling treatments are bullheading and coiled tubing. In the bullheading method, the acid is pumped down the tubing, then the spent acid is lifted to the surface using reservoir pressure. Coiled tubing is another method where the acid is pumped down the coiled tubing, and flowed up through the tubing/coiled tubing annulus.This paper examines the advantages and disadvantages of the two commonly used techniques for tubing pickling: bullheading and coiled tubing. The efficiency of each method is analyzed based on extensive analysis of field samples. In addition, the paper also addresses the effects of acid volume, concentration, and pumping flowrate on the efficiency of removing mill scale from the wellbore.Field data indicated that tubing pickle is a must. Extremely high levels of total iron (up to 105,000 mg/l) were noted in the spent acid. The relationship between dissolved iron and acid concentration profile depended on the mode of acid pumping. In the case of bullheading, the iron peak coincides with the tail of the acid peak, whereas it coincided with the leading edge in the case of coiled tubing. TX 75083-3836, U.S.A., fax 01-972-952-9435.

show abstract

“…Several researchers investigated the type and concentration of these contaminants. [1][2][3][4] The main contaminants present in a typical well tubing are mill scale, iron sulfides, pipe dope, sand, and other fine particles that were picked up during storage and transportation of the tubing string. Oil or condensate may also be present in old producers.…”

Section: Introductionmentioning

confidence: 99%

Lessons Learned from Acid Pickle Treatments of Deep/Sour Gas Wells

Nasr-El-Din¹,

Al-Mutairi²,

Al-Driweesh³

2002

Proceedings of International Symposium and Exhibition on Formation Damage Control

View full text Add to dashboard Cite

Pickle treatments are commonly conducted to remove various contaminants from the wellbore prior to performing chemical treatments in various wells. Introduction of these contaminants into the formation during the treatment can cause loss of well performance, especially in tight formations. These treatments should be designed to remove various contaminants from well tubulars in an efficient and cost effective way.A pickle treatment was designed to clean well tubulars in several wells prior to performing acid fracturing in the carbonate formation. The pickle treatment consisted of several fluids such that each fluid removed one type of contaminants. This paper examines the effects of fluid composition, volume, and placement (bullheading versus coiled tubing) on the efficiency of pickling treatments. More than twenty pickle treatments performed on deep, sour, hot gas wells were examined.To assess pickle treatments in the field, spent acid was analyzed and the concentrations of key ions were measured. Sufficient measurements were made to obtain concentration profiles of chemical species in the spent pickle acid. These profiles were numerically integrated and the data were used to assess the outcome of each pickle treatment. In addition, particulate solids present in the spent acid were separated and analyzed using XRD and XRF techniques.Pickle treatments were conducted on more than twenty gas wells. Some of these wells were perforated, while others were not perforated. Un-perforated wells were pickled using 1.75" high-pressure coiled tubing. On the other hand, perforated wells were pickled using bullheading. The pickle treatments consisted of slugs of surfactants, organic solvents, hydrochloric acid and gelled fluids. Samples of all pumped fluids were collected and analyzed. In addition, well flow back samples were collected every two minutes and were also analyzed to determine their composition.Analysis of spent acids indicated that the major tubular contaminants are mill scale and pipe dope. Spent acid samples collected from deep sour gas wells contained up to nearly 105,500 mg/L of total iron. The efficiency of removing pipe dope was followed by tracing the concentration of zinc, the main acid-soluble constituent in the pipe dope, in the spent acid. The concentrations of acid and iron were used to determine acid reaction with the corrosion products present in the tubing. The concentration of the chloride ions was used to determine the dispersion and mixing behaviour of the acid slug.This paper presents the results obtained from analyzing more than 2000 samples obtained from twenty treatments. The results of this work have been used to enhance the efficiency of the pickle treatments and to significantly reduce the treatment cost. 4 Another main source of wellbore contaminants is iron scale. New low-carbon steel pipes (J-55, C-95 and L-80) are always covered with mill scale (magnetite, Fe 3 O 4 ). 7-10 Iron oxides dissolve in HCl and release ferric and ferrous ions into the acid. Ferric ions will precipitate once th...

show abstract

Scanning Electron Microscope Pictures of Reservoir Rocks Reveal Ways to Increase Oil Production

Cited by 3 publications

References 3 publications

Formation Fines and Factors Controlling Their Movement in Porous Media

Formation Fines and Factors Controlling Their Movement in Porous Media

Tube Pickling Procedures: Case Studies

Lessons Learned from Acid Pickle Treatments of Deep/Sour Gas Wells

Contact Info

Product

Resources

About