Hybrid Sand-Consolidation Fluid Offers Versatility in Treatment of Shallow Reservoirs
Authors: Carpenter Chris 
Published: October 2018

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 189548, “Tunu: From Laboratory to Field Application With a New Hybrid Inorganic/Organic Sand-Consolidation Fluid as Primary Treatment of Shallow Reservoirs,” by J. Andrieu, B. Kutzky, and B.T. Schackmann, Engineered nanoProducts Germany, and A. Mahardhini, SPE, I. Abidiy, SPE, and H.M. Poitrenaud, Total, prepared for the 2018 SPE International Conference and Exhibition on Formation Damage Control, Lafayette, Louisiana, USA, 7–9 February. The paper has not been peer reviewed.

The Tunu giant gas field is in the Mahakam region of the South China Sea. Because of the maturity of the field, the producing layer has moved from the deep zone of consolidated sand into the shallow zone of unconsolidated sand. Hydrocarbon production from the shallow zone is unmanageable without primary sand control downhole. In this paper, a new type of sand-consolidation low-viscous binding material, based on a combination of inorganic and organic components, is presented.

Introduction

Tunu produces almost 40% of total gas production in the Mahakam region. Hundreds of wells have been drilled in the field. Its primary-zone reservoirs are between 2000 and 5000 m true vertical depth (TVD) and typically consist of medium to fine sandstone with strong consolidation and high porosity. Above the primary zone, between 1500 and 2000 m TVD, is the Intra Beta section, with high porosity and sufficient consolidation. In the top layer of the field, shallow reservoirs, above 1500 m TVD, are typically poorly consolidated, with high porosity (28%) and permeability (greater than 1 darcy). Tunu’s shallow zone is an unconsolidated zone that requires sand control; types that have been used include gravel pack, standalone screen, and sand consolidation. Sand consolidation can be a challenging option because of the difficulty in finding a balance between compressive strength and regained permeability after treatment.

Field Application

After the first laboratory-testing phase, detailed in the complete paper, showed promising results, the decision to perform field trials on five wells was validated. Wells in Tunu are typically completed using 3.5- or 4.5-in. tubingless completion inside 7- or 9⅝-in. casing. A coiled-tubing (CT) unit was chosen for pumping into the target reservoir.

First Campaign (2012–2013). The primary objective of the first campaign was to acquire experience with the composite binding material in the field without taking the risk of plugging the wells. Therefore, a large amount [6 pore volumes (PV)] of overflush was used. Several tests and subsequent adjustments were developed to tailor the product to actual field conditions. The first campaign began in October 2012 and ended in July 2013 after treatment on five wells.

On the basis of laboratory test results, the treatment comprises the following steps:

Activation of binding material by dissolving the initiator

Injection of preflush fluid (0.75-fold binding material volume)

Injection of the binding system, followed by a small pill of spacer (maximum 0.5 bbl of preflush)

Post-flushing or overflushing (six-fold binding material volume for first campaign)