A New Approach to Inhibitor Squeeze Design

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractOil field scale treatments can become more difficult when working with deeper non-conventional wells. Inhibitor squeeze is generally the most efficient scale treatment technology. However, inhibitor squeeze treatment is based more on experiences than mechanistic understanding of how the chemical interacts with formation rock and how it flows back.Better mechanistic understanding of the phosphonate/rock interaction is needed to derive innovative squeeze treatment for newer non-conventional wells. Significant progress has been made toward developing a quantitative understanding of the inhibitor/rock interaction, kinetics, stoichiometry, and equilibrium as inhibitors are injected into a formation and allowed to flow back. Four common oil field inhibitors (three phosphonates and one polyacrylate) are compared. In addition to calcite (CaCO 3 ) in the reservoir rock, at least three phosphonate phases appear to be important, a low Ca and a high Ca amorphous Ca-P salts and a crystalline Ca-P salt, where "P" refers to a phosphonate molecule. The inhibitor/rock interaction follows four sequential reactions: (1) Limited acid attack of calcite; (2) Formation of a monomolecular coverage of phosphonate; (3) Reduction of further calcite dissolution due to surface poisoning by the Ca-P coating; (4) Precipitation of Ca-P solid with either low Ca or high Ca stoichiometry. Quantitative relationships between type of inhibitors, inhibitor concentration and acidity, kinetics of calcite dissolution and calcium-phosphonate precipitation are developed for the first time using a rule-based automatic approach. Consequences of the observations on squeeze design and scale inhibition will be discussed.

Overview of the Synthesis of Salts of Organophosphonic Acids and Their Application to the Management of Oilfield Scale

“…Aminomethylenephosphonate groups have excellent chemisorption properties onto the rock matrix as well as fairly good thermal stability, making SIs based around this functional group good for long squeeze lifetimes . The mechanistic understanding of the chemistry of the rock–aminomethylenephosphonic acid (SI) interactions has been reported. , …”

Synthesis and Antiscaling Evaluation of Novel Hydroxybisphosphonates for Oilfield Applications

“…These inhibitors can be synthesized via the Moedritzer–Irani reaction, in which an amine derivative reacts with formaldehyde and phosphorous acid in the presence of hydrochloric acid . For example, aminotrismethylenephosphonic acid ( ATMP ), ethylenediamine tetra methylenephosphonic acid ( EDTMP ), diethylenetriaminepentamethylenephosphonic acid ( DTPM P), hexamethylenediaminetetramethylenephosphonic acid ( HDTMP ), and bishexamethylenetriaminepentamethylenephosphonic acid ( BHMTMP ) are commonly used in the upstream oil and gas industry, particularly for squeeze treatments …”

Effect of Lanthanum on the Crystal Growth of Barium Sulfate

“…Over the years, we have learned, for instance, that growth on the (001) face of barite (or baryte, the mineral name for BaSO 4 ) involves spiral growth at low supersaturations and two-dimensional (2D) nucleation followed by birth and spread at higher supersaturations. , Much of this work has involved relatively pure systems, and information regarding the effect of impurities is dominated by the effect of organic anions . Despite the precipitation of barite being industrially significant for the off-shore oil industry, − studies into the effect of cations on barite precipitation have been limited, even though seawater contains many different cations. In general, the effect of those ions with which barite forms a solid solution (Sr 2+ ), − or are known to incorporate in the lattice (Ca 2+ ), , has been investigated where the impurities were found to alter 2D nucleation shape and rate or morphology.…”