Application of Solid Paraffin Inhibitor in Fracturing of Kuqa Ultra Deep High Pressure and High Wax Content Tight Condensate Gas Reservoir
Authors: Feng Jueyong , Liu Hongtao , Huang Kun , Liu Ju , Yao Maotang , Qin Shiyong , Liu Jiangyu , Wu Bohong 
Published: December 2021

The buried depth of gas reservoir B is more than 6700m, the thickness of reservoir is about 180m, the porosity of reservoir matrix is mainly 5.0% - 7.0%, with an average of 6.3%, and the permeability of reservoir matrix is mainly 0.01-0.1mD, The average production capacity of the three wells is 0.08mD, the formation pressure is 116-126MPa, the formation temperature is 124-131°C, the wax content of the condensate oil is high, and the average wax content is 16.9%. In the early stage, the natural productivity of the three wells was low, and the daily gas production was 120000-180000 cubic meters after stimulation. During the production process, the wellhead temperature was 20°C-25°C, the wax freezing temperature was 35°C, and the wellbore wax plugging was serious, The wellbore was blocked, the gas well was forced to shut down, and the reserves of 100 billion cubic meters were unable to be used, so it was necessary to explore new wax control technology.

Through investigation, a new type of solid particle paraffin inhibitor is introduced, which can enter the artificial fracture with proppant during fracturing. When the condensate gas passes through the fracture, it washes the solid paraffin inhibitor which enters with proppant, and becomes the condensate gas containing paraffin control components.Therefore,it is not easy to form wax after entering the wellbore, which makes the problem of wellbore paraffin formation change from "passive control" to "active control". Referring to the relevant experimental standards, the conductivity, crushing test, solid paraffin inhibitor and fracturing fluid compatibility test were carried out. The existing test standards of wax freezing point are all for waxy oil under normal pressure, but not for condensate gas. A set of innovative experimental method is designed to successfully test the wax freezing point of condensate gas containing wax control components, and obtain the wax control effect under different ratios of wax control agent and proppant, so as to optimize the amount of wax control agent used in the experiment.

The results show that the solid paraffin inhibitor has good dispersibility and suspension, and has little influence on the conductivity of sand filled fractures. The paraffin control effect on condensate oil and gas in this block is good. The wax freezing point can be reduced by about 12°C-18°C, and the optimal dosage is proppant 1%-2%. Field test was carried out in B gas reservoir. After fracturing, 5mm nozzle was used for production, tubing pressure was 83.6MPa, wellhead temperature was 28.8°C, daily oil production was 10.72 cubic meters, daily gas production was 217000 cubic meters, wellhead temperature was lower than wax freezing temperature in this area. At present, it has been in production for 6 months, and there is no wax deposit in wellbore.

The successful test of solid paraffin inhibitor in the fracturing of Kuqa ultra deep high pressure and high wax content tight condensate gas reservoir provides a powerful technical reference for the wellbore flow guarantee of condensate gas reservoir.