【作者】 邢会民；

【导师】 颜其彬； 赵良孝；

【作者基本信息】 西南石油大学 ， 矿产普查与勘探， 2009， 博士

【摘要】 按照天然气储量规范,埋深小于1500m的天然气储层为浅气层。因浅层气藏具有埋藏浅、易于开发和经济高效的特点,越来越吸引着勘探家们的目光。碎屑岩浅气层具有储层埋深浅,岩体弱压实的特征,故其间泥质的压实程度低,孔隙空间及所含流体承受的压力较小。因此使浅气层常具有以下特征:①孔隙度、渗透率和束缚水饱和度相对较高,导致浅气层的电阻率较低。②泥质中粘土矿物晶格内的粘土水含量较高,且随埋藏深度变化明显,使泥质的一系列测井响应参数,如中子含氢指数、体积密度、电阻率等也随之而改变。③天然气的测井响应参数也随深度变化较大,这与中深气层有明显的区别。④储层的产气量不仅与孔隙度、饱和度、有效厚度等参数有关,还与天然气的密度相关,因为对于任何气体,无论其质量多少,它总能充满与之相连通的空间,因此知道它的密度至关重要,也就是天然气对储层的充盈程度,这对于浅气层来说尤其如此。由上可知,碎屑岩浅气层的基本地质特征有别于常规储层。然而,目前针对碎屑岩浅气层的测井评价方法仍采用常规储层的测井评价方法,从而导致储层评价中有3点不足之处:一是未精确考虑泥质对测井响应的贡献使储层参数计算误差较大;二是由于天然气参数变化较大而使流体类型判别失误较多;三是未考虑储层天然气密度,即天然气在储层中的充盈情况,这不仅影响中子孔隙度“挖掘效应”的强弱导致气水判别失误,还会给储层产气量评价造成较大的误差。为此,研究碎屑岩浅气层的泥质校正模型及图版;分析束缚水饱和度的意义和影响因素,讨论现有束缚水饱和度的确定方法及其应用条件和局限性,提出基于常规测井资料的束缚水饱和度的综合计算新方法,研究其计算模型,并与其他方法进行对比;提出充盈度的概念,研究储层天然气密度、地层压力和充盈度的计算模型;最后开展了碎屑岩浅气层测井评价方法的软件编制和应用研究。根据研究成果取得如下认识和结论:(1)碎屑岩浅气层的泥质中子、声波、密度和电阻率参数有别于中深气层,并非固定不变,为此建立的碎屑岩浅气层的泥质校正模型及图板,表明碎屑岩浅气层的泥质参数是埋藏深度的函数。(2)对于流体类型判别,必须采用束缚水饱和度和总含水饱和度共同判别,其关键为束缚水饱和度的确定。(3)基于常规测井资料的束缚水饱和度综合计算新方法是根据钻井液对储层的侵入特征及侵入带中钻井液滤液、束缚水电阻率和束缚水饱和度的关系,利用常规测井资料综合计算求得。此方法区域限制较小,计算方便,在实用中取得了明显效果,因此优于一般的统计计算方法。(4)通常认为储层中子孔隙度曲线与声波时差或密度曲线分离越大,越趋向于气层特征;但当储层天然气密度较大时,高产气层可能误判为水层。在对天然气储层的测井定量评价中,作者认为以往的孔隙度、含气饱和度、渗透率和有效厚度参数难以评价储层产气量。解决这两方面问题必须再引入与储层天然气密度相关的参数,即天然气充盈度来共同评价。(5)首次提出充盈度的概念,即地层温度、压力条件下天然气的密度与标准温度(293K或20℃)、标准压力(0.101Mpa)条件下天然气密度的比值。从而实现利用储层静态测井参数计算储层压力的新途径,进而将储层静态特征与动态特征相结合进行气层评价。(6)碎屑岩浅气层测井评价方法不仅在白马、松华浅气层中计算束缚水饱和度,判别流体类型,结合孔隙度、含气饱和度、渗透率、有效厚度及充盈度参数评估储层产气量取得好的效果,而且用于中深层的苏里格气田也取得较好效果,说明这套方法可以推广应用于一般中深层气田。更多还原

【Abstract】 According to the regulation of gas reservoir,the gas below 1500m under the ground is called shallow layer gas,so the reservoir of that is regarded as shallow gas layer.Nowadays,shallow layer gas reservoir is attracting gradually the expropriators’ sight,because it is shallow,and it is easy and economical to expropriate and develop.The clastic rock shallow gas layer has the characters of lower deep and infirmness compaction, so that the compaction extent of mud and the pressure of pore volume and liquid are low.So,the shallow gas layer has bellowing characters.①porosity,permeability and Swi is relatively high,so that its resistivity is lower.②because of more water in clay of mud and its variety with deep, mud’s parameters will change obviously by the buried depth,such as CNL,DEN and R.③logging parameters of natural gas,such as CNL,DEN and AC,will change by the buried depth, which is obviously different from the middle deep gas layer.④the gas reserves of reservoir is not only related to porosity,permeability,Sw and efficient thickness,but also to the gas density. Because gas is always full of the room no matter what its quality.Thus the gas density is very important.Namely,it is gas full degree for reserves,which is such that to shallow gas layer.Just about the basic characters of shallow gas layer,it is different from the routine reserves when logging evaluation choosing parameters.If we don’t take notice of the important issue,the logging evaluation misplay will be inevitable.As mentioned above,we have found that its reservoir is different from the routine ones. Nowadays,it also introduces to the routine logging method to the evaluation for the Clastic rock shallow gas layer,so,its evaluation result is irresponsible.including three facets.Frist,the account result error of reserves parameters is higher because of disaccurately considering the mud contribution to the logging well response.Second,the misplay to liquid character differentiation is more because of the gas parameters variety.Third,be incapacitated for confirming the gas quality,and do the gas suffuse degree in the reservoir.So,it’s not only to affect the misplay to liquid character differentiation according to theΦ_N excavation effect,but also to make the error of the gas layer reserves.So,the paper has researched the mud adjusting model and chart of the clastic rock shallow gas layer,analyzed the swi sense and affecting factor,discussed the application condition and limitations of the present swi synthetical menthod,provided the new Swi menthod based on routine logging datum,provided the suffuse degree,and researched the reservoir’s gas density model,formation pressure model and the suffuse degree model.Finally,the paper has researched the software program and application study of the clastic rock shallow gas layer evaluaterating method.I have acquired the following recongnization and conclusion according to the research result.(1) The mud’s DEN,CNL,AC and R parameters of the clastic rock shallow gas layer are different from the middle & depth gas layer,and they are vary with the depth according to the mud adjusting model and chart of the clastic rock shallow gas layer.(2) About the fluid type distinguish,it should together distinguish with the Sw and Swi parameters,and the key is to account Swi.(3) The new Swi menthod based on routine logging datum,is based on the drilling fluid’s intrusion feature to the reservoir and the realition between intrusion-related zone’s drilling fluid filtrate,the irreducible water resistivity and the Swi.And the Swi is comprehensively calculated by the routine logging datum.The method hardly affects with the area,and does expediently account,then we have obtain the obvious result to the application.So,it is better than the genergal statistical method.(4) For one thing,it used to be incline to the gas layer characteristic with the the reservoir curve separation increasing between the porosity and the AC or DEN.But which maybe generate that the high production gas layer is judged to the water layer when the reservoir’s gas density is major.For anohter,as to the logging quantity evaluation of the gas layer,which used to be use the porosity,gas saturation,permeability and effective thickness.And it is difficult for the four parameters to evaluate the reservoir’s gas production rate,so,it must be intorduce the suffuse degree parameter which is mutually related the gas density to together evaluate.(5)It’s the first time to provide the suffuse degree,which is the gas ratio between the formation temperature and pressure and the ST(293K or 20℃) and base pressure(0.101Mpa). Thus the new method to calculate the reservoir pressure occurs with the reservoir static state logging parameters,then it has realizen the gas layer with the reservoir static state feature and the dynamic feature.(6) According to the evaluation method of the clastic rock shallow gas layer applying into the Baima and Songhua shallow gas layer,the new Swi menthod based on routine logging datum can accurately calculate the Swi,and accurately distinguish the fluid type.And the reservoir gas production rate is positive correlation with the suffuse degree,and it can be evaluated with the suffuse degree combination with the porosity,gas saturation,permeability and effective thickness. The method is also fit for the Sulige gas field whose layer is middle deep gas ones,so,it can popularize and apply to the other gas field.(6) With the evaluation method of the clastic rock shallow gas layer,it can accurately calculate the Swi and accurately distinguish the fluid type.And it also can evaluate the reservoir gas production rate with the suffuse degree combination with the porosity,gas saturation, permeability and effective thickness.We have acquired the goog effectiveness not only in the Baima and Songhua shallow gas layer,but also in the Sulige gas field whose layer is middle & deep gas ones.So,which shows that the method can popularize and apply to others gas fields.更多还原