Evaluation of Rigless Water Shutoff Treatments to be Used in Arab-C Carbonate Reservoir in Saudi Arabia

Abstract

A multi-lateral oil-producing well A was killed due to excessive water production from Arab-C that is dumping into the Arab-D reservoir. Therefore, the communication between Arab-C and Arab-D where behind the expandable liner is urgently needed to be blocked. Several solutions were investigated in an attempt to stop this flow behind casing. This problem is always a challenging task for field operators. The effect of excess water production on the productive zone, Arab-D reservoir will be substantial in terms of changes in relative permeability of this zone and increased water saturation. This change in the reservoir behavior will result in reduction of well life. The dead well A is a valuable asset that needs to be effectively utilized throughout the producing life of the field. Therefore, remedial treatments to revive this well are of value in terms of strategic plan to maximize revenues. Although the rigless water conformance method in a multi-lateral oil-producing well is a difficult task to the oil companies because of reservoir heterogeneity, cross-flow, gel placement, and cost. Several options of water shutoff treatment are proposed to address remedial treatments for water conformance problems. The main objective of this study is to:Identify and characterize the source of produced water,Identify the chemical blocking agents that will flow through the water out zone, andidentify an effective technique to optimize the size and the placement of these chemicals. Challenges, design criteria, and field treatment evaluation are addressed in this paper. Introduction There are two general methods to minimize water production from Well A: rig workover and rigless operation using coiled tubing unit (CTU). Rig workover operations are very expensive, whereas the rigless operation using CTU is cost effective. A special procedure is needed for gelant placement to minimize the formation damage. The oilfield operator should rely on two distinct types of water production. The first type, usually occurring later in the life of a waterflood, is water that is co-produced with oil as part of the oil's fractional flow characteristics in reservoir porous rock. If the production of this water is reduced, oil production will decrease simultaneously. The second type of water production competes directly with oil production. This water usually flows to the wellbore by a path separate from that for oil (e.g., water coning or a high-permeability water channel through the oil strata). In the latter case, reduced water production can often lead to greater pressure drawdown and increased oil production rates. Obviously, the second type of water production should be the target of water shutoff treatments. Understanding and conceptualizing the reservoir is a key to:Distinguishing between the previous two types of water production.Successfully diagnosing the water production problem.Successfully implementing and designing water shut-off treatments.

Factors Affecting Alkaline Sodium Silicate Gelation for In-Depth Reservoir Profile Modification

“…As the system approaches equilibrium, the gel shrinks and expels the liquid it contains [3]. The first systematic investigation of such syneresis in silicic acid gels was done by Holmes et al [15].…”

“…Na-silicate is thermally stable and more cost-effective than many other types of gel systems [1][2][3]. The gelation of Na-silicate could be controlled by numerous inorganic and organic compounds [4].…”

Polymer Systems for Water Shutoff and Profile Modification: A Review Over the Last Decade

“…This amount increased to 249 million B/D in 2005 (Khatib 2007). Chemical methods include silicate (Grattoni et al 2001;Nasr-El-Din and Taylor 2005;Elewaut et al 2006;Al-Dhafeeri et al 2008;Boye et al 2011), resins (Seright et al 2003), cements, and polymer gels (Seright et al 2003;Sydansk 2007;Lightford et al 2008;Al-Muntasheri et al 2010). Water is also responsible for most of the corrosion and scale problems in the oil field (Donham 1991;Nasr-El-Din 2003;Merdhah and Yassin 2009;Al-Tolaihy and Bukhari 2010).…”

New Developed Acid Soluble Cement and Sodium Silicate Gel to Cure Lost Circulation Zones

“…Typical sodium silicate solution will have a ratio of Na 2 O to SiO 2 as 3.2:1. The advantages of using this system are controllable gelation time, deep gel penetration and low cost, Al-Dhafeeri et al (2008). Stavland et al 2011 mentioned that divalent ions such as Mg (OH) 2 will be precipitated when mixed with sodium silicate so the makeup water needs to be properly designed to be able to pump big quantities of sodium silicate.…”

“…cement and sodium silicate to form plugs for blowout control, Al-Dhafeeri et al (2008). The use of cement to react with sodium silicate requires simple chemistries that are fairly retarded, highly dispersed, and only modified with silica flour at high temperatures, Bauer et al (2005).…”