The Research Of Clastic Rock Reservoir Protection Technology In Tarim Oilfield Hade Block

Reservoir damage evaluation and protection technology, an essential part in the field of oil and gas exploration and development, plays a vital role in improving exploration and development quality. A reasonable evaluation of reservoirs is conducive to the discovery and exploration of them. Reservoir protection is indispensable for increasing economic benefits and ensuring sustainable output in the process of development. Therefore, reservoir protection technology has been obtaining increasing attention with the progress of oil and gas exploration in recent years. Moreover, the technology to analyze and foretell reservoir characteristics and damage potential has also been acquired. Up to now, we are equipped with many protection technologies such as reservoir sensitivity evaluation, reservoir damage criterion and development, fracturing, acdification, etc., which creates huge profits for oilfields.Tarim Oilfield has been suffering a dramatic output reduction in recent years in consequence of reservoir damage caused by long term well drilling, well completion, water injection, and output increase measures. So there is an urgent need to detect the problems existing in this block’s reservoir protection and then come up with some effective countermeasures as well as optimize the drilling fluid used by this block.Reservoir damage can be explained from the following five aspects:(1) Reservoirs are blocked by the dispersed phase particles in drilling fluids.(2) Reservoirs are damaged by the mismatch between drilling fluid filtrate and reservoir rocks.(3) Reservoirs are damaged by the mismatch between drilling fluid filtrate and reservoir fluids.(4) Permeability change causes some damage.(5) The dramatic decrease in negative pressure difference leads to some damage.This thesis focuses its research on the mismatch between drilling fluid filtrate and reservoir rocks and draws some valuable conclusions through lithology analysis of Hade Block in Tarim Oilfield and lithology flow sensitivity evaluation which is carried out under the guide of "Reservoir Flow Sensitivity Evaluation Experiment Methods (SY/T5358-2002)".Lithology analysis shows 3 internal reasons for the potential reservoir damage in Tarim Oilfield:1、Can be seen in the sem figure detrital grain sorting, intergranular pore is development, thin sand layer connectivity medium, Donghe sandstone have good connectivity, so it is possible by solid-phase invasion damage probability.2、From scanning electron microscopy (sem) in the figure can be seen in the sample is located in the rocks on the edge of the pore throat size is large (more than 37 um), so it is not easy to appear the particle migration channel blockage, core may no velocity sensitive.3、See from pictures magnified 3000 times to carved clay mineral is curved lamellar mixed with debris behave affectedly, illite and montmorillonite, the possible/montmorillonite layer, so there may be a reservoir water sensitivity and salt sensitivity.4、The cores there prove relatively sensitive to water and salt after an x-ray diffraction experiment for the analysis of mineral content in clay. The part of clay that minerals account for is from 2% to 10%,7% on average, which illustrates that i/s interstratified minerals are are up to 40%.5、The cores there are not sensitive to flow speed, which can be learned from reservoirs’ relatively good property ,though there is only a small amount of kaolinite and 36% of illite among the 7% of minerals in clay.63、Reservoirs may have weak sensitivity for acids due to the low amount of chlorite in clay.Lithology flow sensitivity experiment verifies the following two aspects:1、Reduce the solid content, reduce the dosage of bentonite, choose matching solid phase particle size, size distribution and quantity, to control the quantity and depth of the solid phase intrusion.Ha De block of Tarim Oilfield is quite sensitive to water, which is in perfect accordance with lithology analysis.2、The cores in Ha De block of Tarim Oilfield present weak sensibility to speed, so the change of flow speed hardly affects permeability.3、Use can inhibit clay swelling of drilling fluid, such as potassium chloride drilling fluid, oil-based mud drilling fluid, the water-in-oil drilling fluid...