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SWEPI LP Well OW 8122 <br />Executive Summary <br />Purpose: Evaluate the cement bond in the well OW 8122. <br />Solution Methodology: Determine the quality of the cement behind the 4 -1/2 ", 11.6# casing in OW <br />8122 using the Schlumberger's Isolation Scanner and CBL -VDL Tools. <br />General: The well OW 8122 is an observation well with a 4 -1/2" casing to 2342ft in a 6 -1/2" <br />borehole. An 11.Sppg pill was spotted at TD prior to running the casing. The casing was cemented <br />with 9.5ppg litecrete light weight cement followed with 15.8ppg class G cement. Plug was bumped <br />with water and 1200psi, tested to 1500psi for 15minutes. During the drilling stages, no cement plugs <br />were placed in the well at various borehole intervals to prevent loss circulation and hence ensure a <br />quality cement job for the casing. <br />The well was logged with the Schlumberger's Isolation Scanner and CBL -VDL Tools on 06- Dec -2012, <br />but the log could reach a depth of 2200ft. Hence the log was reOrun on 12- Dec -2012, after clearing <br />the hole to bottom with the rig. A combined CBL -VDL /Isolation Scanner presentation is in this <br />report. <br />The Schlumberger's Isolation Scanner cement evaluation service provides more certainty for light <br />weight cements by combining the pulse -echo technique with a new ultrasonic technique that <br />induces a flexural wave in the casing with a transmitter and measures the resulting signal at two <br />receivers. The attenuation calculated between the two receivers provides an independent response <br />that is paired with the pulse echo measurement and compared with a laboratory — measured <br />database to produce an image of the material behind the casing. By measuring radially beyond <br />traditional cement evaluation boundaries, Isolation Scanner service confirms zonal isolation. <br />Both the conventional CBL -VDL and ultra sonic pulse -echo techniques rely on a significant contrast in <br />acoustic impedance between the cement and the displaced drilling mud to determine whether or <br />not: a) there is cement behind the casing rather than drilling mud and b) the cement is bonded to <br />the casing and the formation. Due to the use of Tight weight cement in this well which results in <br />lower contrast, the conventional CBL -VDL and ultra sonic pulse -echo techniques have to be <br />supported with the Schlumberger's Isolation Scanner tool. <br />Summary of Findings: The Isolation Scanner Log from the raw curve measurements and all the <br />images indicate Top of Cement (TOC) at 370ft. <br />Three different zones of cement bond log quality can be seen from the analysis as follows: <br />Zone 1 - 1818ft — 2320ft: The flexural image map indicates cement is present in the annulus behind <br />the casing and that casing is bonded. The conventional CBL -VDL log shows low amplitude in this tail <br />slurry cemented interval. The VDL shows presence of formation arrivals in this interval. The <br />transition to lead cement is observed at 1818ft. <br />The high gamma ray responses across the casing joints correspond to Radioactive Tags put in the <br />joints which are 20ft apart. A noticeable change in the cement bond response is seen in the interval <br />2140ft — 2265ft on the scanner image logs, which is possible indication of contaminated cement. The <br />