RIASSUNTO
SPE Members
Abstract
Crude oil flowing from deep reservoirs are exhibiting asphalt deposition in the production tubing. In cases the tubing is getting completely plugged, leading to the loss of production from these wells. production from these wells. Literature on asphaltene deposition in deep wells with high pressure and high temperature is hardly available. To understand the asphalt precipitation and deposition phenomena and its precipitation and deposition phenomena and its control, a comphensive program of work was formlated by the company as indicated below:
1- Laboratory investigation
- asphaltene solubility at various pressures and temperatures - inhibition tests - compositional grading
2- Field investigation
- effectiveness of plastic @ ted tubing - down hole chemical injection - effect of PI improvement on deposition behaviour - chemical means of cleaning the tubing - mechanical means of cleaning the tubing
Progress made so far and future continuation of the work is highlighted in this paper.
In 1978 Kuwait Oil company started a new exploration drilling program. This program proved exceptionally successful. It resulted in the discovery of a new set of lower Jurassic deep reservoirs with a light type of crude. However neither drilling to those reservoirs nor producing from them has been a trouble free producing from them has been a trouble free operation.
The main production problem which is endangering production from these wells and costing a lot of money and effort is the, deposition of asphalt in the production tubing. In this paper light will be shed on the different aspects of this problem and the proposed remedial actions.
ASPHALT AND ASPHALTENES
Asphaltene is a shiny black compound which is chemically defined as the n-heptane insoluble fraction of crude oil by Institute of Petroleum (IP) method of test 143. It consists basically of a condensed aromatic structure including a significant number of hetroatoms (N,S,O) and an alkyle group. Asphaltene is completely soluble in some aromatic solvents like toluene and xylene etc. Figs. 1 and 2 show a pure form of asphaltene sample collected from a problematic well.
P. 377