The Feature and Evaluation of Sandstone Reservoir in the Fourth Section of Xujiahe Formation, Xinchang Gasfield
|School||Chengdu University of Technology|
|Course||Mineral prospecting and exploration|
|Keywords||Xinchang area Xujiahe Tight reservoir Relative quality reservoir Reservoir Evaluation|
New field region of western Sichuan depression Xujiahe four core observation based on the analysis of drill logging data, detailed sedimentary facies analysis, that the study area shall Sec the main braided river delta facies The lacustrine and former Delta -. Which required four subsegmental mainly developed braided river delta phase, before the middle section of the development phase, the lower sub braided river delta facies Delta - littoral and shallow lake. Comparative study on the basis of previous stratigraphic division, according to the deposition of a large number of single well phase sequence analysis, combined with aspect upward changes in the characteristics of the deposition phase sequence, sandstone vertical and horizontal distribution of stability, well logs portfolio characteristics, seismic identifiable Sec will be required to divide 11 sand and sand body horizontal contrast. On previous research foundation, through a lot of rock (cast body) thin section, scanning electron microscopy, cathodoluminescence, and physical properties testing and other analysis means focusing on the study area shall be four on the sub-segment of the TX4-2, TX4-3, X4- 4 groups of sand and under sub-section TX4-8, TX4-9, TX4-10 reservoir characteristics TX4-11 sand group carried out a detailed study. The study area Xujiahe Sec sandstone rock type complex, rich cuttings, maturity structure litharenite, followed by interstitial material for lithic quartz sandstone, carbonate cements and clay minerals. Reservoir sandstones experienced compaction, diagenesis, compaction and cementation cementation and filling the role of dissolution and disruption caused by the loss of reservoir porosity reservoir destructive diagenesis dense, while dissolution, especially the dissolution of soluble components such as feldspar and debris to improve reservoir reservoir, promote reservoir development mainly constructive diagenesis. The study area River group of four reservoir space required to house mainly secondary intergranular and intragranular dissolved pore and mold hole. Pore ??throat distributions multimodal like poor sorting - medium, the reservoir performance is poor. Generally poor reservoir properties, typical of tight reservoir, but local relative quality reservoir development, on subsegmental porosity and permeability relationship is better than the next sub-section, the relatively high-quality reservoir development, or at the lower segment. Comparative study quality reservoir with poor reservoir geological features obtained relatively high-quality reservoir development master factors is a component of rock debris, the depositional environment dissolution paleostructure position and the degree of development of cracks; thus divided layer segment geological prediction model and forecast evaluation criteria, the evaluation of the required four paragraphs a single sand group (body) of the relative quality level of reservoir development.