Novel Sand Conglomeration Treatment Prevents Sand Production and Enhances Well Productivity: Offshore Caspian Case Study

Abstract

Many oil producing wells, globally, experience sand production problems when reservoir rock consists of unconsolidated sand. Several wells in the Dzheitune oil field are experiencing a similar challenge. Production of formation fines and sand has caused accumulation of fill and wellbore equipment failures and has necessitated periodical and costly coiled tubing-assisted wellbore cleanout operations. A novel chemical treatment tested in the oil field to tackle the challenge led to positive results. A well with a relatively short target perforation interval was selected as a candidate for the trial sand conglomeration treatment to avoid any uncertainties related to zone coverage. Pre-requisite sand agglomeration and chemical-crude oil compatibility laboratory studies were carried out to optimize the main system and preflush fluid formulations. Once the laboratory testing was complete, a step-rate test was performed to determine the maximum injection rate below formation fracturing pressure. The chemical systems were prepared using standard blending equipment. The preflush fluid was injected to prepare the treated zone. The main fluid was then injected into the reservoir in several cycles at matrix rate by a bullheading process. Upon completion of the treatment, the well was shut in for several days for optimal agglomeration (conglomeration) before the well was slowly put on production. A long-term increase in the productivity index and sand-free flow rate with no damage to the wellbore or the reservoir were observed. The technology demonstrated its efficiency in preventing and controlling sand production; avoiding frequent, time-consuming, costly wellbore cleanout operations; and producing hydrocarbons at reduced drawdown pressure.

A critical review on analysis of sand producing and sand-control technologies for oil well in oilfields

“…Alfredo et al (Rawlings, 1958;Upchurch, 1999;Tahirov T et al, 2014) injected Zeta potential changing system (ZPAS) into the formation to change the charge distribution on the surface of sand grains, starting from the control of Zeta potential between liquid and solid surfaces. By making the Zeta potential of the sandstone matrix within the range of +3 to -5mV, the electrostatic repulsion between sand particles and between sand particles and between sand particles and reservoir rocks is reduced, which encourages sand particles to aggregate into large clumps (Figure 9) and move closer to reservoir rocks, thus reducing sand migration (Kalabayev et al, 2021). Sand grains can move relative to each other without losing their ionic attraction and can re-aggregate when the stress in the reservoir changes.…”

“…The injected chemical ZAPS does not affect formation wettability or permeability, only changes the surface charge of the solid particles and does not react with other chemicals or minerals in the formation, thereby increasing maximum sand-free production and reducing permeability loss. Kalabayev et al (2021) perform an experimental sand control operation at the Lam oil field in the South Rihedez Sea, Turkmenistan. After this treatment, the target well experienced a long-term improvement in both the production index and the sandfree flow rate, without damage to the wellbore or reservoir.…”

“…Zeta potential sand control technology uses chemicals to change the potential of the sand surface and reservoir rocks, reducing the repulsive force between sand particles and gathering into clumps. Sand particles can still gather again after being dispersed without damaging the reservoir (Kalabayev et al, 2021;Parhizgar Keradeh and Tabatabaei-Nezhad, 2023;Singh et al, 2014).…”