Evaluation of Rigless Water Shutoff Treatments To Be Used in Arab-C Carbonate Reservoir in Saudi Arabia

Abstract

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.