Control Placement of Scale Inhibitors in the Formation With Stable Ca-DTPMP Nanoparticle Suspension and its Transport Porous Media

Abstract

Diethylenetriaminepentatakis(methylene phosphonic acid) (DTPMP) is commonly used in oilfield for scale inhibition. In this study, Ca-DTPMP submicron-sized particles were prepared directly by chemical precipitation with the assistance of phosphino-polycarboxylic acid (PPCA). The influences of adsorbed PPCA, KCl concentration and sonication on the transport and deposition kinetics of Ca-DTPMP particle suspensions in calcite and sandstone matrix were investigated. Adsorption of PPCA to Ca-DTPMP particles increases their negative surface charge and decreases particles deposition in a porous media. The mobility of PPCA-coated Ca-DTPMP particles decreases with increasing KCl concentrations. Using sonication treatments the mobility of Ca-DTPMP particles at high KCl concentration in porous media increased significantly. The retention and long term flow back performance of Ca-DTPMP particles were tested in Frio sandstone columns after 18 hours shut-in time to allow deposition. The results show that enhanced retention of Ca-DTPMP particles and slow dissolution of DTPMP are highly advantageous in slowing the phosphonate release from porous media, and ensuring successful inhibitor treatments in oil fields. Introduction Phosphonates are surface active compounds which are used in a wide variety of industrial applications, including scale and corrosion control, metal finishing, industrial cleaning, dispersants and chelants [1]. One of the most popular applications of phosphonates is to inhibit the formation of scale via a threshold effect, in which a few milligrams per liter of phosphonates or less, is added to the intake water of cooling towers, electric utilities, or oil and gas wells to prevent scale formation[2, 3]. Many oil and gas fields produce 10 to 20 barrels of brine for every barrel of oil (or gas equivalent). These produced brines are generally corrosive and tend to produce calcite or sulfate scales and phosphonates are the most commonly used chemicals to prevent scale formation. In the United States the annual sales of phosphonates exceeds 2 billion dollars per year [4]. In many instances phosphonates encounter high concentrations of divalent metal ions and precipitate as metal salts. In the oilfield application phosphonates are squeezed into the subsurface where they precipitate with divalent cations such as calcium, zinc, magnesium and iron, and then slowly release into the produced fluids during production to inhibit the formation of mineral scale - this is called a "squeeze treatment". Considering the importance of phosphonate precipitates in industrial applications research has been done related to cation-phosphonate precipitation chemistry [5, 6, 7, 8]. A main shortage of the conventional squeeze treatments is that most of the acidic phoshonate is precipitated near the entrance of the formation because the reaction of acid with carbonate and the formation of Ca- phoshonate precipitation take place very quickly. As a result, only limited reservoir protection distance can be provided near the wellbore. Adsorption squeezes are often performed in reservoirs where a neutralized inhibitor pill solution is injected into formation. However, compared with precipitation squeeze, little or negligible amount of inhibitor can be retained and released slowly from the formation. A large fraction of the phosphonate tends to flow back within a few days and then decreases to an extremely low value which is not enough to effectively inhibit scale formation.

A Realistic Look at Nanostructured Material as an Innovative Approach for Enhanced Oil Recovery Process Upgrading

“…Thus, fluid flow through the reservoir pore spaces can be significantly improved with little or no negative impact on the formation permeability, or porous media pore-plugging or chemical trapping related issues that are commonly associated with conventional EOR processes. Shen et al [63] and Zhang et al…”

“…The particles in suspension enhance the performance of the carrier fluid during production owing to high dependency on the unique electrical, rheological, and magnetic properties of the nanoparticles. Since the carrier fluids are normally conventional heat transfer liquids, the particles also enhance the thermal conductivity and convective heat transfer performance of this base liquids as its thermal conductivities are typically an order-ofmagnitude higher than that of the base fluids [9,63]. The nano-based smart fluids display significantly high functional abilities in different systems while reducing the overall fluid cost irrespective of high cost of individual additives [4].…”

“…Generally, nanoparticles regardless of their small particle sizes are easily susceptible to aggregation in liquid suspensions, which promotes surface adsorption of neighboring particles or molecules. This behavior is due to the particles large surface-to-volume ratio and poor wettability in the metal matrix [2,60,61,63]. However, a recent study on nanoparticle adsorption and transport behavior shows that nanoparticle based fluids can efficiently flow A Realistic Look at Nanostructured Material as an Innovative Approach for Enhanced Oil Recovery Process… http://dx.doi.org/10.5772/intechopen.72672 161 through the porous media without excessive adsorption and retention inclinations with an equilibrium adsorption estimation of 1.27 mg/g for 5000 ppm nanofluid [62].…”

Carbon Nanotubes: A New Methodology for Enhanced Squeeze Lifetime CNTs

“…Recently, attempts to improve squeeze treatments and increase squeeze lifetime have been made by a number of means including using crosslinking the inhibitors [2], increasing the pH of the aqueous solution by adding additives [3,4], employing inhibitor particles [5], boosting precipitation and adsorption by additives [6,7], using calcium in precipitation squeeze treatment [8,9] and more recent new ideas such as using fixing agents [10], altering the rock mineralogy [11] and employing nano-particles for further displacement [1].…”

“…Ideally, all the inhibitor injected into the well should be retained within the formation and liberated slowly to maintain the SI concentration above the MIC. However, in practice, a large fraction of the inhibitor, almost a third, flows back after a few days of performing the squeeze [1]. …”