Field Application of Gelling Polymers in Saudi Arabia

Abstract

H.A. Nasr-El-Din, SPE, G.E. Bitar, SPE, F.I. Bou-Khamsin, A.K. Al-Mulhim, SPE and J. Hsu, SPE, Saudi Arabian Oil company (Saudi Aramco) Abstract High water production causes major economic and operational problems for several reasons. It decreases oil production, and results in large amounts of produced water that need to be disposed. It also requires increased capacity of water separation and handling facilities. Other production related problems include high corrosion rates and increased tendency for emulsion and scale formation. Therefore, there is a need to reduce water production. Several mechanical and chemical methods are available for water shut-off treatment. However, the choice of a specific treatment depends on the source of water, well characteristics, and cost. Water shutoff treatments using chemical means include injection of a gelling solution that forms a gel at reservoir conditions. Three main gelling systems are available to conduct water shutoff treatments: a water-soluble polymer with a cross-linker, phenol-formaldehyde resin, and sodium silicate gels. Based on extensive lab studies, two gelling systems were field tested in Saudi Arabia during the last few years. Both gelling systems were applied in a carbonate reservoir. The reservoir temperature is 220-240 F and formation water has total dissolved solids ranging from 45,000 to 200,000 mg/l. The first gelling system consisted of a polyacrylamide polymer, acetate and a retarder. This system was applied in two wells as a means to reduce water production due to coning and bottom water. The second gelling system consisted of sodium silicate with intemal and extemal activators. This system was applied in a well with a high permeability streak. Several operational and quality control problems were encountered during and after field applications. This paper discusses these problems in detail and recommends modifications to these systems to avoid operational problems encountered in the field. Advantages and disadvantages of using several gelling systems are also highlighted. P. 133

A comprehensive review of the chemical-based conformance control methods in oil reservoirs

“…For a successful field application, an adequate gelation time is required to pump the gel solution into the target treatment zone. The polymer and crosslinker type and their concentrations, as well as the reservoir temperature, salinity and pH, can influence the gelation time (Nasr-El-Din et al 1998).…”

Research and Advances of Silicate Plugging Agent in the Oilfields

“…2) The reaction of silicate and fluoride acid: 3) The reaction of silicate and sodium fluosilicate: A silicate system activated by urea-formaldehyde [20] was raised. The urea reacts with OH − in silicate solution, reducing the pH value of the system, and then the silicate ions generated silica gel by condensation polymerization, which is represented in Figure 2.…”