Comparison of gas migration test and building structural strength of slurry in the aspect of limiting gas invasion

Abstract

Lignite opencast extraction can be performed after prior dewatering of the rock mass. Most frequently it is realized with large-diameter dewatering wells which have been mostly drilled with the invert mud rotary method and airlift. This method allows for quick drilling in lithologically diversifi ed aquifers, minimizing the negative impact of mud on the near-well zone. When drilling in dewatered carbonate rocks with the stone runs or well developed karst the effi ciency of this method considerably decreases. The technical and technological aspects of use of downhole ham- mers for drilling large-diameter dewatering wells in diffi cult geological conditions are discussed in the paper. Thanks to the use of this method for drilling wells in ‘Bełchatów’ Lignite Mine the drilling rate could be increased and the number of complications and drilling failures lowered. of natural temperature profi le in aborehole heat exchanger (logger NIMO-T), – thermal response test. The problem of eliminating natural gas microfl ows through the cement slurry while bonding has been investigated by scientists in a number of scientifi c and research centers. Works have been undertaken to defi ne the causes of gas migration and predict possibilities of interchannel communication in the hardened cement slurry. In the course of bonding cement slurry changes its state from liquid through gel to solid. Accordingly, the gas migration eff ects should be taken into account in the formation of these phases. The results of tests of gas migration in the course of binding and building structural strength have been presented in this paper. Both research methods have been compared and a high dependence of parameters defi ned by each of them has been found. The research works were conducted with the use of innovative apparatuses thanks to which the phenomena taking place in the course of binding can be observed. This gives the possibility of working out recipes of sealing slurries applicable to deposits where the risk of occurrence of gas migration is high. Cement sheath serves primarily as a zonal isolation for the life of the well while protecting and supporting the casing. Nowadays, more and more solutions in the term of diff erent cement slurries compositions appear on the market. One of them is application of fl uid ashes as an alternative substitution of cement itself. The purpose of it is to overcome a challenging environment where a high concentration of corrosive gases or fl uids exist. An example of that aggressive substance is carbon dioxide. Moreover, this is how it might reduce the cost of the cementing process. Laboratory research was conducted at the Drilling, Oil and Gas Faculty and Materials Science and Ceramics Faculty at AGH University of Science and Technology in Krakow. The development of conventional and unconventional natural gas reservoir management includes continuous moni- toring of hydrocarbon exploitation processes and its impact on the reservoir and environment. Raman spectroscopy, which allows for the identifi cation of reservoir fl uids (including natural gas) components can be a very promising method for the application of providing a quick, non-invasive, nondestructive analysis. The proposed in this paper measurement methods are focused on the use of: The article presents the basic technical assumptions for measurements of the composition of natural gas with the use Raman spectroscopy. Various organic and inorganic compounds can be used as hydration inhibitors. The main purpose of this paper is the examination of fi ve diff erent ionic hydration inhibitors: KCl, K 2 CO 3 , HCOOK, NH 4 Cl, CaCl 2 . The paper contains the survey fi ndings of the infl uence of the above mentioned inhibitors diff erent concentrations on technological parameters of drilling muds with a dual inhibitor system and swelling of clays. Correctly performed intake wells are a warranty of long and effi cient exploitation of the object. A number of import- ant factors are involved, starting from the correct technology of drilling to proper supervision of the investor and control of realization of particular stages of work. These factors are typical of each stage of the investment process, from the stage of determining project requirements, quality of drilling to commissioning of the well. For this reason it is extremely important for the investor to establish the requirements and technical criteria which will be presented to the authors of the geological project and potential performer of the well. Geological works can be successfully verifi ed with available diagnostic techniques, thanks to which the quality of performance can be recognized, make the contractor remove construction failures and improve the effi ciency of hydraulic well before fi nal commissioning. The necessity of performing such an analyses should be included in the budget of the planned well. Properly defi ned technical condition of the drilled well and evaluation of its hydraulic effi ciency, being a basis for commissioning, allows the designers to select rational parameters of production and elongate a well’s life.