... and damaging the permeability of the formation. In many cases the residual polymer has limited solubility in acid solutions, making it difficult or impossible to remove the damage, although, with time, these wells will slowly cleanup and the production will increase. The long time to cleanup is one...

... Abstract This paper introduces a new retarded stimulation system which is based upon an environmentally friendly, biodegradable acid and highlights its first field trial in a sandstone/granite formation. Here, demanding borehole conditions (165°C, anhydrite and carbonate scales, highly...

... Abstract An existing limitation of chelant-based fluids available for sandstone acidizing with hydrofluoric acid (HF) is the presence of sodium in the concentrate of the aminopolycarboxylate fluid, which is common in all chelating agents soluble below pH 3.5. The presence of sodium complicates...

... wells, focusing on stimulation design, lessons learned from the fluid testing, experiences, and the continuous improvement of the operational execution process. New producer and injector stimulation designs are generally based on a pad-acid procedure in which a cross-linked gel pad is followed...

... Abstract Viscoelastic surfactants (VES) have been widely used in acidizing and acid fracturing. They are used as diversion agents during matrix acid treatments and leakoff control agents during acid fracturing. At high temperatures, viscoelastic surfactants hydrolyze, resulting in phase...

... Abstract The growing demand for well-designed weighting agents to overcome the currently drilling challenges such as ECD management and the settling tendency of the weighting agents led to the development of a new micronized ilmenite (FeTiO 3 ). The acid solubility of ilmenite is of great...

... Abstract Sandstone acid systems, which are composed of HCl and HF, are commonly used to remove the formation damage in sandstone reservoirs. However, to perform any treatment using these acid systems, a preflush and/or a postflush of HCl plain acid must be injected to eliminate CaF 2...

.... In this scenario, a self-diverting acid system based on a viscoelastic surfactant (VES) technology was introduced for carbonate reservoir stimulation. The Self-Diverting VES (SD-VES) promotes viscosity development when the acid comes in contact with the carbonate formation. The mechanism of viscosity development...

... Abstract Regular mud acid mixtures have been extensively used to stimulate sandstone formations; however, the use of this acid in a deep well has some major drawbacks, including high and uncontrolled reaction rate and corrosion to well tubulars. A single stage sandstone acid system (HF...

... of using reactive liner shaped charges on the outcome of matrix acidizing treatments and to compare the performance of reactive and conventional charges for different charge types and loads. Cream Chalk cores with 7 in. diameter × 24 in. length were perforated with two weights of reactive and conventional...

... pressure acid injector well University Prologue The field This field was discovered in 2000 by Total Upstream Nigeria Ltd (TUPNI). Located 150 kilometers off the Niger Delta at a water depth of 1,400 meters, it is the first deep-offshore development involving light oil with high gas content...

... is the general solution for determination of acid (or other recipes) treatment volume required to effectively remove the damaging materials in the near wellbore region of a horizontal well. Specific expression of the Ģ, X i , Y i and Z i terms are as shown below; (9) G = 3 N 3 (10a...

... Abstract Iron sulfide scale deposition is a common problem in sour oil and gas wells. Accumulation of iron sulfide in the production tubing causes reduction of well deliverability. Conventional chemical means to remove Iron sulfide scale usually involve hydrochloric acid and other mineral acids...

... Abstract Chelating agents are used in the oil and gas industry mainly to: remove inorganic scales, control iron during acid treatments, and stimulate carbonate/sandstone reservoirs. The main chelating agents used in the field, include: ethylenediaminetetraacetic acid (EDTA), N-(hydroxyethyl...

... cleaning fluids. The reaction of selected organic acids and chelating agents with Mn 3 O 4 particles as a function of time and temperature were studied. Atomic absorption was used to measure manganese concentrations and X-ray diffraction to analyze solids remaining after the reaction. White precipitate...

... Abstract The KKY in Tarim oilfield, Western China, is a typical HTHP deep dolomite reservoir (150C, 110Mpa and 6000m). The formation was deeply damaged with the heavy mud, and the matrix acidizing can't effectively eliminate the skin. But the acid fracturing treatment can't be carried because...

... Abstract In offshore operations where seawater is commonly used to prepare hydrochloric acid, calcium sulfate precipitation, the potential of which can greatly reduce the effectiveness of these treatments. This is because high concentreation of calcium produced in spent acid mixed with high...

... and/or matrix acidizing techniques. Conventional matrix stimulation treatments require the use of straddle packers to ensure complete zonal coverage and frequently result in increased water production with no significant increase in oil production, making the treatments uneconomical. To reduce the cost...

... Abstract Mixtures of HCl-HF, known as mud acid, have been extensively used in sandstone matrix stimulation. However, mud acid treatments were applied with poor success rate. This is mainly due to complex acid/rock interactions and other factors, such as the presence of HCl-sensitive clays...

... Abstract In oil fields, serious difficulties with acid-induced sludge, a major source of well damage, can vary from a viscous, stable emulsion. A chemical analysis of sludge shows that hydrochloric acid (HCl) is present in the sludge structure. Also, Fe(III) ions in HCl formulations can cause...