| It is one of the major problems that sand production in oil wells troubled the development of unconsolidated sandstone reservoir, the sand is not only easy to reduce production of oil well even stop production, aggravate wear and tear of equipment both on the ground and underground, but also cause the casing to be damaged and the oil well to be scrapped when the sand production is serious. Therefore, in order to ensure the oilfiled to keep a stable and high yield, we must take some effective measures to solve the problem of oil well sand control.In the completion process, the screen pipe selection and the compatibility of drilling fluid, the carrying capacity of screen pipe for the paticles that from mud cake in the drilling fluid, are also important factors that affect oil flowing into the oil pipe through the sand control device near the wall of oil well. Through the analysis of the particle size of drilling fluid and the matching analysis research that between screen pipe and drilling fluid, we can effectively solve the contradiction between sand prevention and oil production.This thesis described both domestic and foreign oil wells about sand prevention status and technology. It confirmed the sand influx and the median value of strata sand particle size with sieve analysis method and laser diffraction analysis (LDA) that was used for sand sample of the main wells like XJ24-3and XJ30-2in XiJiang oilfiled to quantify the reservoir sand particle size analysis, and predicted the extent of reservoir sand production with core observation method, porosity method, the Schlumberger ratio method, combined modulus and the sonic time difference method that five methods. We selected optimally a sand retaining accuracy as the goal of neither had a serious sand invasion nor affected productivity greatly through to simulate the sand influx by sand device accoding to the production of every stimulant horizontal well in laboratory. Through the analysis in particle size of drilling fluid and the matching analysis research that between screen pipe and drilling fluid, the laboratory evaluated the performance of the PRO-FLO drilling fluid system comprehensively, and we could obtain the following results:1) With five kinds of sanding prediction technique to predict the situation of sand production on every layer of XJ24-3-2X well and XJ30-2-2X in XiJiang oilfield, we may conclude that:both in XJ24-3and XJ30-2, there are some layers have sand production tendency, which belongs to a slight sanding category. And it is necessary to take some measures to prevent sand production form normal development. 2) It is known by laser particle size analysis that the median D50of the sand sample particle size that according to the HI reservoir of XJ24-3-A25well on the spot is approximately220microns and the uniformity coefficient is1.85. The sand sample is from fine sand; The median D50of the sand sample particle size that according to the H2reservoir is approximately355microns and the uniformity coefficient is2.33. This sand sample is from uniform sand; The median D50of the sand sample particle size that according to the H3reservoir is approximately310microns and the uniformity coefficient is2.31. This sand sample is from uniform sand; The sand sample, of which the median D50of particle size that according to the H4reservoir is approximately360microns and the uniformity coefficient is2.43, is from uniform sand. According to XJ30-2-2X well on the spot, the median D50of the sand sample particle size that from H3A reservoir is approximately403microns and the uniformity coefficient is4.44. The sand sample is from uniform sand; The median D50of the sand sample particle size that from HC reservoir is approximately230microns and the uniformity coefficient is1.94. The sand sample is from fine sand; The median D50of the sand sample particle size that from H3reservoir is approximately246microns and the uniformity coefficient is2.41and the sand sample is from fine sand.3) Through to study loose sand of every layer about sand-filling and sand-prevention model, we found that sand influx met the sand control standard of oil and gas well when the aperture of screen pipe was250μm in the H1layer and the H3layer of XJ24-3-A25well and the HC layer and the H3layer of XJ30-2-2X well. When the the aperture of screen pipe was300μm, the sand production rate of the H2layer and the H4layer of XJ24-3-A25was more appropriate. The sand retaining accuracy about the HB layer of XJ30-2-2X was150microns.4) By the study of screen pipe about permeability, the main drilling fluid additives of XiJiang oilfield should be biodegradable starch treatment agent, the particle size should be as small as possible. It is recommended that the size is less than300mesh,so that you can avoid plugging of granular material on the screen pipe to solve the screen clogging problem.5) It is proved by experiment that PRD drilling fluid system and PRO-FLO drilling fluid system have good rheological control ability, At a temperature of70℃to110℃, every system has a better ability to withstand high temperature; The two sets of solid free system have a good performance of anti-contamination; And both they have a good performance of lubrication. The Inhibition performance and filtration control of the two sets of solid free system can be adjusted according to the quantity changes of different finishing agent.6) After the study, wo conclude that when using two sets of water-based drilling fluid to drill on the spot, it is recommended to take250micron sieve net in the H1layer of XJ24-3-A25well; It is recommended to take300micron sieve net in the H2layer of XJ24-3-A25well; It is recommended to take150micron sieve net in the HB layer of XJ30-2-2X well. In consideration of sand production rate, flow rate, productivity and the nature of output fluid comprehensively, it is suggested that we should take gel-breaking method to drilling fluid when field operations. |
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