Gas compressibility factor or z-factor plays an important role in many engineering applications related to oil and gas exploration and production, such as gas production, gas metering, pipeline design, estimation of gas initially in place (GIIP), and ultimate recovery (UR) of gas from a reservoir. There are many z-factor correlations which are either derived from Equation of State or empirically based on certain observation through regression analysis. However, the results of the z-factor obtained from different correlations have high level of variance for the same gas sample under the same pressure and temperature. It is quite challenging to determine the most accurate correlation which provides accurate estimate for a range of pressures,

On-site pit is the most common option that may be used to dispose drilling wastes. The contents of these pits vary, depending on the lithology of formations drilled and the drilling mud ,and different chemical additives.
Eighty samples of mud (sludge) and eighty samples of water have been collected from ten pits of two Iraqi oilfields(North Rumaila and South Rumaila/southern Iraq) and were chemically analyzed for metals Cr, Pb,As, Zn, Fe, Mn,K , Na,Ba, Ca, Mg,SO4=,and Cl- in order to determine the quality and quantity content of studied reserve pits
Inefficient equipment, using toxic materials for various drilling processes, absence of regulations for the design and monitoring of pit during and after drilling operation, and leaking

The thermal maturity ,  burial history and petroleum generation history of  four oil wells selected  from four oil fields in Southern Iraq, they are: Nasiriyah(Ns-1 well) , Gharraf (GA-5well) ,Abu Ammood (Ab-1well) and Riffai (Ri-1well) have been studied using 1D basin and petroleum systems modeling. Results showed  different period of subsidence, which ranges from high to moderate subsidence, occurred at upper Jurassic to Mid-Cretaceous and slow subsidence in Miocene  . The porosity in the studied area represents the highest value in Dammam , Tayarat ,Um-Eradhuma and Khasib Formations. For most of the studied wells, the Paleocene to Miocene has to be regarded as times when the maximum temperature prevailed assoc

In the field of research in the investment of gas fields, this requires that we first look at the center of the contracting parties in terms of the guarantee means granted to them under the contract, which constitute a means of safety and motivation to enter as major parties in the investment project. In turn, we will discuss the minimum guarantees, which are the most important guarantees granted to each of the two parties to the contract, namely the national party and the investor.

It is evident from this study that Yamama Formation is reservoir rocks and source rocks at the same time, based on occurrences of crude oil and source rocks. Bulk properties of Yamama oil in six wells as well as comparing several samples of Yamama oil by using the biological mark have indicated multi source of hydrocarbons with some pay having Jurassic and Lower Cretaceouse source affinity that belongs to the Yamama Formation.