Optimum Injection Rate of a New Chelate That Can Be Used To Stimulate Carbonate Reservoirs

2010 ◽  
Author(s):  
Mohamed Ahmednasreldin Mahmoud ◽  
Hisham A. Nasr-El-Din ◽  
Corine De Wolf ◽  
James N. LePage
Keyword(s):  
Injection Rate ◽  
Carbonate Reservoirs ◽  
Optimum Injection Rate

Optimum Injection Rate of A New Chelate That Can Be Used To Stimulate Carbonate Reservoirs

SPE Journal ◽  
2011 ◽  
Vol 16 (04) ◽  
pp. 968-980 ◽  
Author(s):  
M.A.. A. Mahmoud ◽  
H.A.. A. Nasr-El-Din ◽  
C.A.. A. De Wolf ◽  
J.N.. N. LePage
Keyword(s):  
Acetic Acid ◽  
Ethylenediaminetetraacetic Acid ◽  
Injection Rate ◽  
Carbonate Reservoirs ◽  
Damkohler Number ◽  
Optimum Conditions ◽  
The Core ◽  
Damköhler Number ◽  
Optimum Injection Rate ◽  
Injection Rates

Summary Different chelating agents were used as alternatives for hydrochloric acid (HCl) in matrix acidizing to create wormholes in carbonate formations. Previous studies demonstrated the use of ethylenediaminetetraacetic acid (EDTA), hydroxy ethylenediaminetriacetic (HEDTA), and glutamic acid-N,N-diacetic acid (GLDA) as standalone stimulation fluids to stimulate carbonate reservoirs. The main problem of using EDTA and HEDTA is their low bio-degradability. GLDA was introduced as a standalone stimulation fluid for deep carbonate reservoirs where HCl can cause corrosion and face dissolution problems. In this study, calcite cores 1.5 in. in diameter and 6 or 20 in. in length were used to determine the optimum conditions where the GLDA can break through the core and form wormholes. GLDA solutions with pH values of 1.7, 3, and 3.8 were used. The optimum conditions of injection rate and pH were determined using coreflood experiments. Damköhler number was determined using the wormhole length and diameter from the CT scan 3D and 2D images. GLDA was compared with chelates that are used in the oil industry such as EDTA and HEDTA. GLDA also was used to stimulate parallel cores with different permeability ratios (up to 6.25). GLDA was found to be very effective in creating wormholes at pH = 1.7, 3, and 3.8; at different injection rates; and at temperatures up to 300°F. Increasing the temperature increased the reaction rate and less volume of GLDA was required to break through the core and form wormholes. Unlike HCl, in GLDA there was no face dissolution or washout in the cores even at low injection rates (0.5 cm3/min). An optimum injection rate and Damköhler number were found at which the pore volume (PV) required to create wormholes was the minimum. GLDA at pH 1.7 and 3 created wormholes with a small number of PV (at 1 cm3/min, GLDA at pH 1.7 required 1.5 PV at 300°F, and at pH 3 it required 1.8 PV). Compared with acetic acid, the volume of GLDA at pH 3 required to create wormholes was less than that required with acetic acid at the same conditions. GLDA was found to be effective in stimulating parallel cores up to 6.25 permeability contrast (final permeability/initial permeability).

A Matrix Acidizing System for Controlled Carbonate Well Stimulation using a Carboxylic Acid Salt with a Chelating Agent

2021 ◽  
Author(s):  
Albert Bokkers ◽  
Piter Brandenburg ◽  
Coert Van Lare ◽  
Cees Kooijman ◽  
Arjan Schutte
Keyword(s):  
Chelating Agent ◽  
Life Time ◽  
Nitrogen Atmosphere ◽  
Injection Rate ◽  
Sodium Gluconate ◽  
Matrix Acidizing ◽  
Well Stimulation ◽  
Stirred Reactor ◽  
Core Flood ◽  
Optimum Injection Rate

Abstract This work presents a matrix acidizing formulation which comprises a salt of monochloroacetic acid giving a delayed acidification and a chelating agent to prevent precipitation of a calcium salt. Results of dissolution capacity, core flood test and corrosion inhibition are presented and are compared to performance of 15 wt% emulsified HCl. Dissolution capacity tests were performed in a stirred reactor at atmospheric pressure using equimolar amounts of the crushed limestone and dolomites. Four different chelating agents were added to test the calcium ion sequestering power. Corrosion tests were executed using an autoclave reactor under nitrogen atmosphere at 10 barg. Core flood tests were performed to simulate carbonate matrix stimulation using limestone cores. It was found that the half-life time of the hydrolysis reaction is 77 min at a temperature of 100 °C. Sodium gluconate and the sodium salt of D-glucoheptonic acid were identified to successfully prevent the precipitation of the reaction product calcium glycolate at a temperature of 40 °C. Computed Tomography (CT) scans of the treated cores at optimum injection rate showed a single wormhole formed. At 150 °C an optimum injection rate of 1 ml/min was found which corresponds to a minimum PVBT of 6. In addition, no face dissolution was observed after coreflooding. Furthermore, the corrosion rates of different metallurgies (L80 and J55) were measured which are significantly less than data reported in literature for 15wt% emulsified HCl. The novelty of this formulation is that it slowly releases an organic acid in the well allowing deeper penetration in the formation and sodium gluconate prevents precipitation of the reaction product. The corrosivity of this formulation is relatively low saving maintenance costs to installations and pipe work. The active ingredient in the formulation is a solid, allowing onsite preparation of the acidizing fluid.

The New Flow Control Devices Autonomously Controlling the Performance of Matrix Acid Stimulation Operations in Carbonate Reservoirs

2021 ◽  
Author(s):  
Mojtaba Moradi ◽  
Michael R Konopczynski
Keyword(s):  
Flow Control ◽  
Dynamic Change ◽  
Injection Rate ◽  
Control Flow ◽  
Carbonate Reservoir ◽  
Operating Conditions ◽  
Carbonate Reservoirs ◽  
High Permeability ◽  
The Impact ◽  
Stimulation Of

Abstract Matrix acidizing is a common but complex stimulation treatment that could significantly improve production/injection rate, particularly in carbonate reservoirs. However, the desired improvement in all zones of the well by such operation may not be achieved due to existing and/or developing reservoir heterogeneity. This paper describes how a new flow control device (FCD) previously used to control water injection in long horizontal wells can also be used to improve the conformance of acid stimulation in carbonate reservoirs. Acid stimulation of a carbonate reservoir is a positive feedback process. Acid preferentially takes the least resistant path, an area with higher permeability or low skin. Once acid reacts with the formation, the injectivity in that zone increases, resulting in further preferential injection in the stimulated zone. Over-treating a high permeability zone results in poor distribution of acid to low permeability zones. Mechanical, chemical or foam diversions have been used to improve stimulation conformance along the wellbore, however, they may fail in carbonate reservoirs with natural fractures where fracture injectivity dominates the stimulation process. A new FCD has been developed to autonomously control flow and provide mechanical diversion during matrix stimulation. Once a predefined upper limit flowrate is reached at a zone, the valve autonomously closes. This eliminates the impact of thief zone on acid injection conformance and maintains a prescribed acid distribution. Like other FCDs, this device is installed in several compartments in the wells. The device has two operating conditions, one, as a passive outflow control valve, and two, as a barrier when the flow rate through the valve exceeds a designed limit, analogous to an electrical circuit breaker. Once a zone has been sufficiently stimulated by the acid and the injection rate in that zone exceeds the device trip point, the device in that zone closes and restricts further stimulation. Acid can then flow to and stimulate other zones This process can be repeated later in well life to re-stimulate zones. This performance enables the operators to minimise the impacts of high permeability zones on the acid conformance and to autonomously react to a dynamic change in reservoirs properties, specifically the growth of wormholes. The device can be installed as part of lower completions in both injection and production wells. It can be retrofitted in existing completions or be used in a retrievable completion. This technology allows repeat stimulation of carbonate reservoirs, providing mechanical diversion without the need for coiled tubing or other complex intervention. This paper will briefly present an overview of the device performance, flow loop testing and some results from numerical modelling. The paper also discusses the completion design workflow in carbonates reservoirs.

Comparison of Wormhole Profiles on Carbonate Rocks Using Emulsified and Single-Phase Retarded Acids

2022 ◽  
Author(s):  
Norah Aljuryyed ◽  
Abdullah Al Moajil ◽  
Sinan Caliskan ◽  
Saeed Alghamdi
Keyword(s):  
Organic Acids ◽  
Single Phase ◽  
Injection Rate ◽  
Flow Rates ◽  
Low Viscosity ◽  
Propagation Behavior ◽  
Additional Equipment ◽  
Acid Reaction ◽  
Optimum Injection Rate ◽  
Indiana Limestone

Abstract Acid retardation through emulsification is commonly used in reservoir stimulation operations, however, emulsified acid are viscous fluids, thus require additional equipment at field for preparation and pumping requirements. Mixture of HCl with organic acids and/or chemical retarders have been used developed to retard acid reaction with carbonate, however, lower dissolving power. Development of low viscosity and high dissolving retarded acid recipes (e.g., equivalent to 15-26 wt.% HCl) addresses the drawbacks of emulsified acids and HCl acid mixtures with weaker organic acids. The objective of this study is to compare wormhole profile generated as a result of injecting acids in Indian limestone cores using 28 wt.% emulsified acid and single-phase retarded acids at comparable dissolving power at 200 and 300°F. Coreflood analysis testing was conducted using Indiana limestone core plugs to assess the pore volume profile of retarded acid at temperatures of 200 and 300° F. This test is supported by Computed Tomography to evaluate the propagation behavior as a result of the fluid/rock reaction. Wider wormholes were observed with 28 wt.% emulsified acid at 200°F when compared to test results conducted at 300°F. The optimum injection rate was 1 cm3/min at 200 and 300°F based on wormhole profile and examined flow rates. Generally, face-dissolution and wider wormholes were observed with emulsified acids, especially at 200°F. Narrower wormholes were formed as a result of injecting retarded acids into Indiana limestone cores compared to 28 wt.% emulsified acid. Breakthrough was not achieved with retarded acid recipe at 300°F and flow rates of 1 and 3 cm3/min, suggesting higher flow rates (e.g., > 3 cm3/min) are required for the retarded acid to be more effective at 300°F.

scholarly journals Improved CRM Model for Inter-Well Connectivity Estimation and Production Optimization: Case Study for Karst Reservoirs

Energies ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 816 ◽  
Author(s):  
Daigang Wang ◽  
Yong Li ◽  
Jing Zhang ◽  
Chenji Wei ◽  
Yuwei Jiao ◽  
...  
Keyword(s):  
Time Delay ◽  
Net Present Value ◽  
Water Injection ◽  
Injection Rate ◽  
Production Optimization ◽  
Carbonate Reservoirs ◽  
Karst Reservoir ◽  
Control Step ◽  
Multi Phase Flow

Due to the coexistence of multiple types of reservoir bodies and widely distributed aquifer support in karst carbonate reservoirs, it remains a great challenge to understand the reservoir flow dynamics based on traditional capacitance–resistance (CRM) models and Darcy’s percolation theory. To solve this issue, an improved injector–producer-pair-based CRM model coupling the effect of active aquifer support was first developed and combined with the newly-developed Stochastic Simplex Approximate Gradient (StoSAG) optimization algorithm for accurate inter-well connectivity estimation in a waterflood operation. The improved CRM–StoSAG workflow was further applied for real-time production optimization to find the optimal water injection rate at each control step by maximizing the net present value of production. The case study conducted for a typical karst reservoir indicated that the proposed workflow can provide good insight into complex multi-phase flow behaviors in karst carbonate reservoirs. Low connectivity coefficient and time delay constant most likely refer to active aquifer support through a high-permeable flow channel. Moreover, the injector–producer pair may be interconnected by complex fissure zones when both the connectivity coefficient and time delay constant are relatively large.

Influence of Transport Conditions on Optimal Injection Rate for Acid Jetting in Carbonate Reservoirs

2018 ◽  
Author(s):  
Dmitry Ridner ◽  
Taylor Frick ◽  
Ding Zhu ◽  
A. Daniel Hill ◽  
Renzo Angeles ◽  
...  
Keyword(s):  
Injection Rate ◽  
Carbonate Reservoirs ◽  
Optimal Injection

Influence of Transport Conditions on Optimal Injection Rate for Acid Jetting in Carbonate Reservoirs

2020 ◽  
Vol 35 (01) ◽  
pp. 137-146
Author(s):  
Dmitry Ridner ◽  
Taylor Frick ◽  
Ding Zhu ◽  
Alfred Daniel Hill ◽  
Renzo Angeles ◽  
...  
Keyword(s):  
Injection Rate ◽  
Carbonate Reservoirs ◽  
Optimal Injection

scholarly journals MODELING AND OPTIMIZATION OF ACID TREATMENT OF FHF FRACTURE IN CARBONATE RESERVOIRS

2015 ◽  
pp. 45-52
Author(s):  
G. T. Bulgakova ◽  
A. V. Blonsky
Keyword(s):  
Acid Treatment ◽  
Pressure Field ◽  
Treatment Effectiveness ◽  
Mass Conservation ◽  
Injection Rate ◽  
Carbonate Reservoirs ◽  
Acid Transport ◽  
Fracture Width ◽  
The Face ◽  
The Subject

The subject of the study presented is a process of acid treatment of a fracture generated by FHF using proppant in carbonate reservoirs. For prediction of acidizing treatment effectiveness the averaged mathematical model of this process was developed based on the laws of acid mass conservation and acid transport in fractures taking into account the acid solution leakage due to diffusion towards the treated surface. The modeling aids in the pressure field predic-tion, as well as the acid concentration profile along the fracture and the fracture width variation resulted from the face etching, and the skin factor as a function of injected acid amount and injection rate.

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