METHOD FOR CONTROL OF TIGHTNESS OF COUPLING JOINTS OF A PRODUCTION STRING AND DETECTION OF INTERVALS OF GAS ACCUMULATIONS IN OPERATING GAS WELLS WITH STATIONARY NEUTRON METHODS

摘要

FIELD: oil and gas industry.;SUBSTANCE: invention relates to gas industry and can be used for control of tightness of coupling joints of production strings (PS) in operating gas wells, as well as to detect intervals of gas accumulations in PS using multi-probe neutron logging. Method comprises recording current intensities of epithermal neutron fluxes at small – J_nnl.et.sp and large – J_nnl.et.lp probes of neutron logging by epithermal neutrons, and current intensification of flows of thermal neutrons on a small probe – J_nnl.t.sp. Current readings of said probes are normalized to their readings in water (J_{nnl.et.sp.w.,} J_{nnl.et.lp.w.,} J_nnl.t.sp.w.) and in the process of constructing diagrams of variation of said normalized readings from the depth of the gas well, determining the intervals for finding coupling couplings PS, where negative abnormal values are observed – J_{nnl.t.sp.norm.}, and gas accumulations behind separated clutches are determined by increment of readings J_{nnl.t.sp.norm.} relative to readings of said probe, recorded in depth above and below coupling connections PS. At that, complete substitution of cement filling of annulus space with gas cluster is set by increase of readings J_{nnl.et.sp.norm.} 2.0–2.2 times and increase of readings J_{nnl.et.lp.norm.} not more than in 1.3–1.5 times relative to background values. According to recorded exceedances of 1.4–1.5 times normalized indications of intensity of epithermal neutron fluxes on a small probe of 2NNLet – J_{nnl.et.sp.norm.} above the registered normalized readings of the intensity of epithermal neutron fluxes on the large probe of 2NNLet – J_{nnl.et.lp.norm.} determining gas accumulation in cement stone behind production string.;EFFECT: technical result consists in expansion of analytical capabilities of neutron methods, which enable to solve problem of control of coupling connections PS for air-tightness and detection of gas accumulations in PS operating gas wells.;3 cl, 4 dwg