Experimental study of acidizing diversion effect on different permeability of heterogeneity sandstone reservoirs

Du, Juan; He, Y.F.; Liu, Pingli; Guo, Jun; Zhao, Liqiang

doi:10.1007/s13202-019-0642-9

Cited by 7 publications

(5 citation statements)

References 23 publications

(15 reference statements)

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“…According to the Darcy formula of porous media (1), when a heterogeneous reservoir is stimulated by an acid, the amount of acid in each small area is proportional to its permeability. 21 After the acid is injected into the reservoir, a large amount of acid enters high-permeability areas and increases reservoir heterogeneity. As shown in Formula 1 , the fluid viscosity can be improved so that the acid reaches each layer.…”

Section: Methodsmentioning

confidence: 99%

Experimental Study on the Diversion Characteristic of a Viscous Fluid in a Heterogeneous Reservoir

Liu

Lan

et al. 2022

ACS Omega

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As a typical feature of a reservoir, heterogeneity is the main reason for low oil recovery and the poor effect of acidizing measures. Diversion is the main measure to improve the acidizing effect. Over the years, technological progress has mainly focused on the material development of diverting agents. In this study, the diverting effect and influencing factors for a viscous fluid were systematically studied by the heterogeneous dual-core flooding experiment. The results are as follows: First, increasing the displacement pressure in heterogeneous reservoirs can improve the diverting effect, which is consistent with maximum differential pressure and injection rate (MADPIR) theory, but the diverting effect is weak. The injection pressure difference is increased by 50 times, and the diverting effect is improved by 16.27% at most. Second, taking a viscous fluid as the stimulation fluid can partially realize the diversion for heterogeneous reservoir and further improve the acidizing effect, and the breaking through PV can be improved by 78% at most. Using a viscous fluid as a diverting agent can achieve 100% balanced acid injection. Third, compared with a viscoelastic surfactant, a relatively uniform and stable polymer solution as the diverting agent has the possibility to completely block the low-permeability layer. So, a 5% viscoelastic surfactant as the diverting agent is more suitable for acidizing. Finally, any diverter injected into the formation will enter all layers. The conclusion that the diverting agent only enters the high-permeability layer but not the low-permeability layer is not tenable. Diverting acidizing is only effective for near-well zones, which is difficult to fundamentally solve the seepage problem of heterogeneous reservoirs.

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Section: Methodsmentioning

confidence: 99%

Experimental Study on the Diversion Characteristic of a Viscous Fluid in a Heterogeneous Reservoir

Liu

Lan

et al. 2022

ACS Omega

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“…VES are commonly used in carbonate reservoirs as self-diverting agents when formulated with acids. [2,7,13,14] They have become a popular agent due to their polymerfree chemistry. [15] Various studies [7,16] have documented the rheological properties of VES, which depend on shear rate and are controlled by formulation parameters like surfactant chemistry, concentration, temperature, acid strength, reaction products, and additives like corrosion inhibitors.…”

Section: Introductionmentioning

confidence: 99%

“…Screening acid concentration up to 20 wt.% HCl and surfactant concentration up to 8 wt.% resulted in higher diversion efficiency at acid strength of 5%–10% with 6% VES and testing temperature of 60°C. [ 14 ] In this study, the acidic diverting formulation combined hydrochloric acid, amphoteric surfactant, CaCO 3 as source of CaCl 2 , and a corrosion inhibitor to protect testing equipment. The synthetic cores were pre‐saturated in decane and then flushed with brine prior to VES pill injection.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of viscoelastic surfactant‐based diverting agent during the chemical treatment of sandstone reservoirs

Moghaddam¹,

Doorn²,

Santos³

et al. 2022

Can J Chem Eng

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The challenges of diversion during the stimulations of carbonate formations have been widely studied for decades. It has been shown that viscoelastic surfactants (VES) are among the effective diverting solutions which can be used during the stimulation of carbonate formations. These chemicals benefit from the reaction products between the acid and the calcite to increase the viscosity of the acid, therefore reducing, temporarily, the permeability of the first invaded rock layer, which holds the highest permeability. This temporary blockage steers the remaining acid to the layers with lower permeability that need treatment. This is usually called self‐diverting acidizing treatment. However, the same approach may not necessarily be applied for sandstone formations that are not calcite rich. In such cases, combining acid stages with batches of diverting agents is still feasible. For this approach, VES is also a suitable, non‐damaging solution that is often overlooked. In this study, the application of VES as a diverting agent was investigated during the chemical treatment operations in sandstone formations. Several dual core‐flooding experiments were performed at high pressure and high temperature (HPHT) conditions using sandstone core samples with high permeability contrast.

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“…Solutions containing wormlike micelles (WLMs) are useful in several applications such as well stimulation, − drag-reduction in pipes, − and also as drug delivery agents. − WLMs can be formed when the molecules of block copolymers or viscoelastic surfactants (VESs) aggregate at concentrations above the critical micelle concentration (CMC). WLMs provide both viscous and elastic properties to aqueous solutions when entangled, making the solutions like polymer solutions .…”

Section: Introductionmentioning

confidence: 99%

Deducing the Relation between Viscosity and Oil-Induced Structural Changes of Viscoelastic Surfactants Using a Kinetic Approach

et al. 2021

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The present study relates viscosity reduction with time of a wormlike micellar solution to the micellar transitions that occur with time in the presence of three n-alkanes, namely, n-decane, n-dodecane, and nhexadecane. Steady-shear rheology and small-angle X-ray scattering were used to deduce the relationship. The effect of n-alkane concentration was tested only with n-decane. There were at most three stages of viscosity reduction, which appeared in the following order: (i) the rising viscosity stage, (ii) the fast viscosity reduction stage, and (iii) the low-viscosity stage. The stages and rates of viscosity transition depended on the type of micelles present and the degree of micelle entanglement. Moreover, the rate of transition increased when the nalkane concentration was increased and when the n-alkane molecular mass was reduced. n-Hexadecane induced only the first two stages of transition at a slower rate compared to the other oils.

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Experimental study of acidizing diversion effect on different permeability of heterogeneity sandstone reservoirs

Cited by 7 publications

References 23 publications

Experimental Study on the Diversion Characteristic of a Viscous Fluid in a Heterogeneous Reservoir

Experimental Study on the Diversion Characteristic of a Viscous Fluid in a Heterogeneous Reservoir

Evaluation of viscoelastic surfactant‐based diverting agent during the chemical treatment of sandstone reservoirs

Deducing the Relation between Viscosity and Oil-Induced Structural Changes of Viscoelastic Surfactants Using a Kinetic Approach

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