Achieving Zonal Isolation by Using New-Generation Mud Removal Chemistry and Design Methodology to Displace Non-Aqueous Drilling Fluid

Abstract

The criteria for success of any primary cementing job is achieving permanent zonal isolation. Incomplete mud removal will affect the zonal isolation in several different ways and may lead to the development of a communication channel in the annulus and subsequently jeopardize the well integrity. Nonaqueous fluids (NAF) are incompatible with cement slurries; the quality of the cement placement and set properties will be strongly affected by the presence of the NAF residue down hole. Although this problem can be mitigated through the addition of various chemicals providing compatibility, mud-thinning, reduction of the interfacial tension, and water-wetting functions, the current surfactants and solvents on the market have limited application in terms of temperature and type of drilling fluids. In addition, the current API/ISO testing protocols are generic and results are not reproducible. Recently, improved laboratory procedures have been proposed and these improved experimental methods were used on more than 200 surfactants and solvents. A screening process helped in selecting the optimum chemistry as a function of the conditions (type of base oil, salinity, temperature). This enabled developing design guidelines to select an optimized tensioactive package comprising a limited number of chemicals, from which field users would select the ones to combine for their applications. The new tensioactive package was used successfully in two field trial wells in the 7-in. liner sections in a mature development field offshore Thailand. After a thorough comparison between the currently used package and the new one, the laboratory results using the field mud show superior cleaning results and efficiency with the new chemical package. The zonal isolation was confirmed using an ultrasonic imager logging tool. After the two successful field trials, the tensioactive package was selected as the spacer of choice for a critical new development field campaign offshore Thailand in which zonal isolation between production zones was critical for selective production from each of the zones separately. This paper will describe the newly improved laboratory methodology and selection criteria of the new tensioactive products and provide a detailed case history of the application in the development campaign, including the design, execution and evaluation of the job.

Review of Developments in Nanotechnology Application for Formation Damage Control

“…Furthermore, failure to achieve a high-strength cement bond between the casing and the rock formation might lead to further issues and formation damage: blockage of pore channel networks in wellbore regions when cement filtrate manages to invade the formation, interaction between cement additives and reservoir fluids resulting in scaling, clay reactions and silica dissolution, formation of fluid leakage, contamination of fresh water and formation fluids, and fluid loss during injection. ,, This formation damage leads to a decline in the permeability and productivity of the reservoir, resulted in a high cost of remedy with uncertain success…”

Nowe rodzaje cieczy przemywających osady z płuczki inwersyjnej przed zabiegiem cementowania otworów wiertniczych

“…Poprzez dobór odpowiednich środków powierzchniowo czynnych możliwe jest także zmniejszenie objętości zatłaczanych cieczy i skrócenie czasów płukania otworu, zmniejszając przy tym ilość powstałych odpadów wiertniczych [2,6,9,14,15].…”

Application of nanoparticles for strengthening wellbore cement-formation bonding

“…1). Globally, previous oil-well integrity reports indicate that 4.6% of the 316,000 wells surveyed in Alberta had leak problems [7]. Around 13-19% of the producing wells and 37-41% of the injection wells encountered leakage in the North Sea's Norwegian region [8,9].…”

“…The least allowable shear bond strength for oil-well cement is 100 psi (0.689 MPa), in compliance with the American Petroleum Institute (API) specification 10A [12]. In this regard, several studies are conducted regularly focusing primarily on enhancing the bond strength at the cement-formation interface to boost well integrity and productivity [7,[13][14][15]. During the last few years, numerous researchers have concentrated on the use of nanoparticles to increase cement efficiency.…”