Fig. 1—Example of the change-mapping technique applied to a core sample. The after-test image (a) shows a drilling mudcake attached at the top, which is not present in the before-test image (b). Image (b) is subtracted from image (a), leaving behind the change (c). A reservoir-conditions coreflood study was undertaken to assist with design of drilling and completion fluids for a Norwegian field. Multiple fluids were tested, and the lowest permeability alterations did not correlate with the lowest drilling-fluid-filtrate-loss volumes. This paper will examine the factors that contributed to alterations in the core samples. A range of measurements are made during reservoir-condition studies, with typical metrics of the performance of a fluid or sequence including the following: These metrics are unfortunately subject to a number of factors that make interpretation difficult and therefore add risks to the decision-making process. In order to reduce these risks, a number of interpretive techniques are used. These include scanning electron microscopy (SEM), thin sections, and computed-tomography (CT) scanning. In order to overcome some of the limitations posed by existing techniques, a micro-CT change-mapping technique was developed to show the distribution of alterations within samples at selected points in a study. This article, written by Technology Editor Chris Carpenter, contains highlights of paper , “The Nature of Drilling-Fluid Invasion, Cleanup, and Retention During Reservoir-Formation Drilling and Completion,” by and Corex; Aker BP; and University of Stavanger, prepared for the 2017 SPE Bergen One Day Seminar, Bergen, Norway, 5 April. The paper has not been peer reviewed. ... This article is reserved for SPE members and JPT subscribers. If you would like to continue reading, please , or
A research paper on the design of drilling and completion fluids for a North Sea oilfield found there was no direct connection between oil - based drilling - fluid - filtrate loss to the formation and formation conditions caused by the drilling fluid . Damage is more likely to be caused by the drilling - fluid filter cake sticking to the formation , according to the study by Corex , Aker BP and the university of Stavanger . It involves simulating the operational situation at reservoir conditions , gathering data to analyze data , in order to minimise operational risk .