Exploration • Drilling • Field Services


Kenneth Søndervik introduces a new wireline tool that utilises backscatter X-ray imaging.


Kenneth Søndervik introduce una nueva herramienta alámbrica que utiliza imágenes de rayos X de retrodispersión.


Kenneth Søndervik stellt ein neues Wireline-Werkzeug vor, das Röntgenverfahren mit Rückstreuung verwendet.


X-ray imaging for oil wells W hen equipment


becomes lost, stuck or malfunctions deep in an oil well, operators have few resources


available to investigate the problem. Fishing expeditions to retrieve the equipment are time-consuming, expensive and frequently unsuccessful when carried out by personnel who are effectively blind to the downhole situation. As a result, many different tools and methods have been developed to visualise objects in a well.


Te oldest method is the lead-


impression block technique, in which a soft block of lead is lowered to the depth of interest and deformed to the shape of the object encountered. Once the block is brought back to


the surface, it is inspected to provide information about the object. While this method is fast and inexpensive, the impression can often be difficult to interpret and may not provide enough information to solve the problem.


3D information


An alternate technique uses standard ultrasonic imaging. Tis method has the advantages of providing 3D information about the structure of interest and


operating in a fluid-filled well. However, it requires precise knowledge of the speed of sound in the specific fluid to produce good quality images, and the images suffer when the fluid has too much heterogeneity (eg, a fluid with gas bubbles or suspended solid particles). Te frequent and large changes in density in such cases cause excessive absorption and scattering of the beam. Te third commonly used downhole imaging technique is straightforward optical video and/or images. Although images or movies produced are easy to understand, the image quality depends greatly on the clarity of the well fluid and the ability to keep the lenses clean. Often this means expensive and time-consuming operations swapping opaque fluids or fluids with a high concentration of suspended solid particles with clean fluid before performing optical imaging. Tese deficiencies in the currently


available tools and methods have led to the proposal that X-rays could be used for imaging in oil wells.


Fig. 1. Visuray’s VR90 tool uses ground-breaking X-ray technology to provide precise downhole images irrespective of well fluid.


Penetrating opaque materials Te ability of X-rays to penetrate through opaque materials is well-known from imaging applications in the medical and security fields, where a technique called radiography is frequently used to image the interior of the human body, luggage or other containers. One of the principal limitations of radiography is that it requires access to an object from at least two sides. For imaging in an oil well, as well as many other applications, accessing opposite sides of an object of interest is often not possible. In such cases, a second type of X-ray imaging that utilises photons scattered backwards from the object can be used. Backscatter imaging is commonly used in security applications where it is desirable to see objects located behind an opaque barrier without needing to physically remove the barrier, such as for vehicle or container inspection and luggage or personnel scanning.


www.engineerlive.com 19


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84