Towards a Complete Removal of Barite Weighted Water and Oil Based-Drilling Fluids in Single Stage

Abstract

Barite is one of the most common weighting materials used in drilling fluid for deep oil and gas wells. Consequently, the main source of solids building the filter cake is the weighting material used in drilling fluids ‘Barite particles’. Barite is insoluble in water and acids such as HCl, formic, citric, and acetic acids, as well as the barite has low solubility in chelating agent such as Ethylene Diamine Tetra Acetic Acid (EDTA). The present study introduces a new formulation to dissolve the barite filter cake using converters and catalysts. Barite can be converted to barium carbonate at high pH medium using combination of potassium hydroxide (KOH) and potassium carbonate (K2CO3) solution. Then HCl acid can be used to dissolve the barium carbonate. Another solution is to use high pH EDTA chelating agent and potassium carbonate as a catalyst/converter in one step. The removal formulation also contains polymer breaker (oxidizers). The three components of the new formulation are compatible and stable up to 300°F. Solubility tests were conducted using industrial barite particles with size ranged from 30 to 60 micron. The solubility experiments were carried at 300°F for 24 hours. Different concentrations of catalyst were added to select the optimum concentration. The designed formulation was examined to remove filter cake formed by Barite drilling fluid using High Pressure High Temperature cell (HPHT). The result of this study showed that the barite removal efficiency of new formulation reached to 87 % in water base mud and 83 % in oil base mud. The solubility test results presented that the solubility of barite particles in 0.6M EDTA was 62 % in 24 hours at 300°F. Adding potassium carbonate catalyst to the 0.6M EDTA solution the increased the solubility of barite to 90 wt. % in 24 hours. The use of converting agents increased the barite solubility from62% to 90% in EDTA. The EDTA was compatible with the polymer breaker (oxidizer) so the filter cake removal will be in single stage. The oxidizer concentration used was 10 wt%, potassium carbonate concentration was 10 wt% and EDTA concentration was 0.6M. The new formulation achieved 85% filter cake removal in both oil-based and water-based drilling fluids. In oil base mud a water wetting surfactant, mutual solvent, and emulsifier should be added to the formulation to remove the oil. In this study, two solutions were proposed to remove the barite filter cake and barite scale from oil and gas wells at different conditions. The first one is by using HCl acid after converting the barium sulfate to barium carbonate using high pH medium such as KOH and K2CO3. Then HCl can easily remove the barium carbonate. The second method is to create the high pH medium by using the removal fluid itself which is EDTA chelating agent in addition to potassium carbonate as converter.

Applications of Chelating Agents in the Upstream Oil and Gas Industry: A Review

“…Nevertheless, using enzymes as polymer breakers requires further studies on the compatibility of the chelating and polymer breakers. The available information displayed the compatibility in limited cases. ,, Furthermore, as in other applications, such as EOR, the combination of more than one chelating agent improved the performance. Hence, it would be interesting for future research work to develop such combined solutions to overcome some of the usage limitations.…”

“…For example, oxalic acid proved to be an efficient catalyst/convertor when used with DTPA for barite dissolution . In another study, a significant enhancement in barite dissolution was achieved when potassium carbonate was used as a synergist for DTPA . Almost 95% of barite was dissolved using a combination of potassium carbonate and DTPA.…”

“…68 In another study, a significant enhancement in barite dissolution was achieved when potassium carbonate was used as a synergist for DTPA. 75 Almost 95% of barite was dissolved using a combination of potassium carbonate and DTPA. Sodium EDTA has lower dissolution compared to potassium EDTA.…”

Barite Removal Using Macropa: Simulation and Solubility Investigations

“…Barite is insoluble in water and regularly used solvents such as hydrochloric acid (HCl), formic acid (CH 2 O 2 ), and citric acid (C 6 H 8 O 7 ). − It has low solubility in combination with chelating agents such as hydroxyethyl ethylene diamine tri-acetic acid (HEDTA) and ethylene diamine tetra-acetic acid (EDTA). − The solubility of barium sulfate is less than 2.3 mg/L, and the solubility product ( K sp ) is around 10 –10 M 2 at 25 °C. , Therefore, barium sulfate will precipitate in different forms during the drilling and production operations. Barite presents around 50–80% of the filter cake that results from drilling a well, and also different types of scales can be induced due to the accumulation of barite minerals. ,, Deposition of barium sulfate can take place within the production system as well as inside the formation, leading to considerable damage .…”

Rheological properties and damage-control mechanism of oil-based drilling fluid with different types of weighting agents

“…In an application where the density is high, however, the suspension of the standard barite is not stable and can easily be affected by temperature and pressure, which will seriously affect the drilling speed and also increase the probability of accidents [8]. By far, many studies on barite surface modification have been conducted to improve the weighting ability of the barite, such as increasing the zeta potential on the barite's surface, enhancing its lipophilicity/hydrophilicity and strengthening its suspension stability [9,10]. For the drilling fluid with high density, however, a large amount of barite will cause the problem of rheological stability.…”