Evaluation of a New Barite Dissolver: Lab Studies

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. ProposalBarite is a common weighting agent used for oil well applications. It is commonly used to provide adequate weight to control downhole pressures in drilling slurries. Since it is used for control of pressure, it is a common source of formation damage, especially in deep, hot formations where drilling fluid weights exceed 17 ppg. Although alternatives do exist for barite, (e.g., formate drilling fluids) they are significantly more expensive, and not available on a rapid turnaround basis as in emergency situations required by well control operations. Once damage has occurred, remediation is a very difficult proposition. Barite is not soluble in typical oilfield inorganic acids used in stimulation. The most common methods of remediation are fracture stimulation and/or deep perforations. The use of these methods can remediate the problem, but at high cost. Also, since the well productivity cannot be evaluated prior to stimulation operations, a poor quality well cannot be identified until a significant investment has been made.The most common chemicals currently in use to address this problem are "barite dissolvers". These agents are all strong metal ion chelators. Aminopolycarboxylic acids (e.g., EDTA) and similar reagents have been used with low success rates. 1 Recently, hydroxylaminopolycarboxylic acids were introduced, but to the best of the author's knowledge was not extensively used in the field. 2 This study investigates a new barite dissolver and compares its performance with other commercial dissolvers. The new material is a proprietary dissolver supplied in a liquid form. This study investigates the dissolving capacity, and evaluates the effectiveness of the dissolver by conducting coreflood tests. These tests were conducted using sandstone cores obtained from a deep gas well (300ºF). The effectiveness of the dissolver was followed by measuring the concentration of barium in the core effluent. Unlike other barite dissolvers, the new chemical is shown to be very effective in restoring the permeability of damaged cores. The new chemical does not require long soaking times, and does not induce fines migration due to chemical means.

Evaluation of the Reaction Kinetics of Diethylenetriaminepentaacetic Acid Chelating Agent and a Converter with Barium Sulfate (Barite) Using a Rotating Disk Apparatus

“…It contains five carboxylate groups, which bind to the metal center containing three N 2 atoms. 16,22 The ligands form strong chelates with a ratio of 1:1 in high pH solutions. Although DTPA could be sodium-or potassium-based, our previous study shows that barite has high solubility in potassium-based DTPA.…”

“…9,11−17 Acids, such as hydrochloric acid (HCl), formic acid, citric acid, and lactic acid, are ineffective in dissolving barite solids. 16,17 Therefore, chelating agents, such as diethylenetriaminepentaacetic acid (DTPA), ethylenediaminetetraacetic acid (EDTA), and hydroxylethylethylenediaminetriacetic acid (HEDTA), were introduced as alternatives to dissolve barite. 13,16−18 DTPA chelating agent yielded the maximum dissolution capacity of barite.…”

Barite Removal Using Macropa: Simulation and Solubility Investigations

“…A higher pressure drop and lower rock permeability will be obtained once the barite minerals are deposited within the porous medium. Solubility tests can be used to measure the removal efficiency of chemical treatments. , Higher barite solubility will indicate efficient barite removal. Ion concentration measurements and molecular simulations can be used to understand the removal mechanism, hence helping in improving treatment efficiency …”

Improved Method for Use of Chelation to Free Stuck Pipe and Enhance Treatment of Lost Returns

“…Similar compounds, variations, mixtures, and new dissolving compounds are also being developed. [3][4] This paper explores the use of chelation agents for a different application. Rather than remove scale or barite within the formation, the objective is to remove barite that composes the filter cake.…”